Tire Pressure Max

[deebrown]

I heard that inflating the tires to max pressure will increase stability and I would like to try that out - does anyone know what the tire pressure max is on the P185/60R15 that come with the car?

[ROCKLANDTOYOTA]

44 LBS....

[seymour201]

It says it right on the tire

[BailOut]

We hashed this all out in another thread that you can search for if you'd like deeper information, but here's the skinny:

Max sidewall pressure is the *minimum* pressure you should use on the Yaris. Several of us on CleanMPG.com run the RE92's at 60 PSI and have gotten not only nice MPG increases (due to lower rolling resistance) but much greater life out of the tires (the first of us to go to 60 PSI just hit 85,000 miles on the original tires - that's unheard of at 32 PSI).

Toyota's recommendation of 32 PSI is based solely on a comfortable, cushy ride rather than anything to do with performance, stability, tire wear, etc.

[jamal1984]

We hashed this all out in another thread that you can search for if you'd like deeper information, but here's the skinny:

Max sidewall pressure is the *minimum* pressure you should use on the Yaris. Several of us on CleanMPG.com run the RE92's at 60 PSI and have gotten not only nice MPG increases (due to lower rolling resistance) but much greater life out of the tires (the first of us to go to 60 PSI just hit 85,000 miles on the original tires - that's unheard of at 32 PSI).

Toyota's recommendation of 32 PSI is based solely on a comfortable, cushy ride rather than anything to do with performance, stability, tire wear, etc.

so what you said is we can put the pressure on the yaris to 60psi? my is at 40 now, i'm worry that i'm pump over 44 the tires will blow in my face, that is one scary shit.

If it true i will do it for sure man.

[5spBlazer]

Im running 50PSI right now.

[AlphaFox]

what kind of MPG increases are you seeing running at 50 or 60 psi? (up from stock)

[brickhardmeat]

There is a "thingy" in your glove box called an Owner's Manual, comes "free" with the Yaris. Try opening it up. Theres lots of words in there and "stuff":rolleyes:

[BailOut]

what kind of MPG increases are you seeing running at 50 or 60 psi? (up from stock)

That's a hard one to answer because your driving style really plays into it. If you're a regular, everyday kind of driver then you will see maybe 0.5 - 2 MPG, just because it's easier for your engine to make the car roll if it doesn't have to fight the tires so much.

If you hypermile then the benefits shoot through the roof. For example, on my commute home there's a section of the mountain road that is just very slightly downhill for almost a mile. I used to have to use fuel in this area but with the tires at 60 PSI I can turn off the engine (and then go back to Ignition II to keep PS/PB for a while) and coast that entire section without dropping speed. I can pull a similar stunt for about another mile at the bottom of the mountain after going through the clover leaf on-ramp. I can use it twice again in my subdivision for another half mile each time after accelerating to 40 in a 45 MPH zone. I can stealth coast from the main subdivision road through 4 90-degree turns and right up my driveway and into my garage.

[PetersRedYaris]

Not to bring you guys down, but, this is a really bad idea. Max pressure is called that for a reason. You do know your tires heat up with highway speeds so even putting them at 44 means they are running far higher than that with sustained speed. Setting them at 60PSI means they could go over 70 with summer heat and fast driving. Blow-out time!

[BailOut]

Not to bring you guys down, but, this is a really bad idea. Max pressure is called that for a reason. You do know your tires heat up with highway speeds so even putting them at 44 means they are running far higher than that with sustained speed. Setting them at 60PSI means they could go over 70 with summer heat and fast driving. Blow-out time!

Back in the 1970's you would have been right, Peter. However, since that time consumer tires have been steel belted which prevents this from happening. The worst that could happen on just about any modern tire is some uneven and/or early tread wear.

I commute over a mountain every day in snow or sun at 60 PSI without issue. As I mentioned earlier a fellow hypermiler who does a lot of highway driving just hit 85,000 miles on his RE92s, which is literally impossible at 32 PSI. We are just 2 out of a pool of folks that have been running at 60 PSI for quite some time now not only without issue but with several tangible benefits.

[SailDesign]

I'm with Peter on this one. Max pressure is listed so that you know what NOT to inflate above, for safety reasons. You may indeed get better mpg, but other things like braking and cornering will be adversely affected, and should you have an accident through a blow-out, and it is found all your other tires are over-inflated, you will have a hell of a fight with your insurers.
Would you ride with 11 other people in an elevator rated for 6, just because it saved energy going down? I thought not.....
Getting another 2 mpg out of a car that is already capable of over 35 is not enough of an incentive, IMNSFHO

[BailOut]

... but other things like braking and cornering will be adversely affected, and should you have an accident through a blow-out, and it is found all your other tires are over-inflated, you will have a hell of a fight with your insurers...

Actually, the inverse is true about braking and cornering since there is no tire sag to deal with. The higher pressure offers much better handling, not worse. Try it for yourself.

You have a valid point about insurance companies because they are generally uneducated about such matters. I do not bow to a lack of education... I educate the uneducated.

[Chris07LB]

(the first of us to go to 60 PSI just hit 85,000 miles on the original tires - that's unheard of at 32 PSI).


:eyebulge: For real? On your '07 you have 85k already? :bow:

[Doc Zaius]

Might be an '06 if its from Canada... we got them earlier than you guys.

But wow... 60 PSI... thats nuts. I won't feel so bad about overinflating a little bit now.

(also the first time I'ver heard the term hypermiler!) :biggrin:

[SailDesign]

Actually, the inverse is true about braking and cornering since there is no tire sag to deal with. The higher pressure offers much better handling, not worse. Try it for yourself.

You have a valid point about insurance companies because they are generally uneducated about such matters. I do not bow to a lack of education... I educate the uneducated.

Up to a point, higher pressure helps. I'm at 43psi right now on 205/45-16s, and it works well even in rain. But, too high a pressure reduces the contact patch with no increase in coefficient of friction, since the tyre/tire becomes more brittle at a certain load level and fractures (at an almost microscopic level) rather than grips. The trick is in finding the "sweet spot" for your tyres and car. There was a good article on tyre physics in... someone help me out, here - one of the Sports Compact/GrassRoots Motorsport/Modified mags recently. Well worth reading.
"Inverse"? Is that the same as "opposite", but for edjimacated folks?

[Black Yaris]

you guys running 60 psi are not the brightest bulbs in the pack are ya... expacially on the shit ass stock potenza that came stock on the car, 1st the car has to ride like a brick, 2nd the is a safty issue, by over inflating the tires you risk seperating the tire and at that pressure it would most likely blow out.
general rule of thumb, over inflating is not a good idea

BailOut, I think you would be safer doing a "bailout" on the freeway than driving with 60 psi

and for that guy that got 85k on his stock potenza's... I am sure he had plenty of tread left.... on the outside edge of his tire, there had to be non left on the inside at that psi, and plus the increased psi from heating them up on the e-way in NV (1psi per 10 deg)

[eTiMaGo]

BailOut, I think you need to procure some tread pictures or other proof if you wanna continue with this :wink:

[churp]

I agree with BailOut that tires last 85,000 miles if you drive like Grandma with a very light car....My Dad changed the tires on his 83 Mazda pickup at 109,000 not because of the tread but the sidewalls were ready to blow! And I also agree 60psi will help gas milage but it is unsafe as hell...probably manslaughter charge from the family of the person you kill (if they ever find out you hade 60 psi in your tires--total neglect of safety notices from tire and car manufacturers)

:evil: .5 to 2 mpg isn't worth it

Just because you're sober doesn't mean your not responsible!

[BailOut]

http://www.officer.com/article/article.jsp?siteSection=19&id=27281

[Black Yaris]

I think this will trump your source guy

http://www.betiresmart.ca/inflation/placard.asp?loc1=inflation&loc2=placard
http://www.rma.org/tire_safety/tire_maintenance_and_safety/tpms.cfm
http://www.tiresafety.com/

[BailOut]

Umm, Black Yaris, what are you trying to show with those 3 links? I don't see what information they contain that you are trying to convey.

One just apes the old adage about following the vehicle manufacturer's recommendation, another says people don't check their tire pressure, and the last doesn't say anything except it provides a shamelss plug for Bridgestone who, of course, would much prefer you run your tires ragged in 20,000 - 30,000 miles rather than 85,000+.

If I missed anything there feel free to correct me.

[churp]

In the 3rd link under the 'MAINTENENCE' section....it states to NEVER inflate passenger car tires above the listed pressure on the tire.....as an engineer I can only assume this means the manufacturer has limits to his liability and states it clearly here....how clearer can it get? You may never have a blowout at 90psi...but just like drinking and driving, if you go beyond prescribed limits you are personally responsible for your actions if something goes wrong.

As for the driving instructor...I didn't see any credentials other than he has taught 'so&so many'. Butt dynos don't show failure point, strength of materials, dynamic loads, etc. so where does he base his knowledge on tire pressure science?

Max pressure listed on the tire is just that....it's there for a reason.

[PetersRedYaris]

Bailout- It's totally cool if you want to do this on your own car, but why would you recommend a possibly dangerous modification to other people who may or may not know better? Wouldn't you feel bad if they had a blowout and someone got hurt as a result? Gamble with your own life, and if YOU have a blow-out and harm another individual, I hope you take responsibility for your actions.

[BailOut]

We keep coming back to what I first said...

Pump up your tires to *at least" the max sidewall. If you are still uncomfortable with that statement then read it as "Pump up your tires to max sidewall."

If you want to go higher you can and there are many people that do and and have done so for quite a while.

However, as with all other things hypermiling you certainly don't *have* to do it if you don't wish to, whatever your reasons. Just take the information, assimilate it, and make your own decisions.

On a side note, for a bunch of folks that are willing to swap out engine, exhaust, suspension, tire size and width and just about any other components on a whim you sure are ultra conservative when it comes to tire pressure and oil change intervals. hehe


Edit: Peter, that is way over the top and totally uncalled for. Please do not make such unfounded alarmist statements. Hundreds of people between the Prius and general hypermiling communities representing over a million collective miles of driving on all kinds of roads and in every condition run at higher than max sidewall, and over a 5 or 6 year period not a single incident of a blown tire or this pressure contributing to an accident has come to light.

[eTiMaGo]

Well he's not forcing anyone to run 60PSI, just sharing his experience, observations and research.

It is entirely up to the individual to follow or not, but if you are interested, why not try a halfway point, like 45-50PSI? It's definitely safer than under-inflated tyres! (which reminds me, I gotta check my pressure...)

[eTiMaGo]

hahha jinx!

[SailDesign]

Welcome to the CleanMPG forums.


Some posts may describe situations which may in some cases be unsafe or illegal in some jurisdictions. Please use common sense and consult your local laws to make sure you do not hurt yourself or others or break any laws.



Need I say much more? Oh, OK, then...

I can discuss but cannot personally recommend upwards of 25% higher then MAX sidewall as there are legal constraints we all have to live with.

[BailOut]

I can discuss but cannot personally recommend upwards of 25% higher then MAX sidewall as there are legal constraints we all have to live with.

44 x .25 = 11
44 + 11 = 55

So go with 55 PSI instead of 60 if it makes you feel better. :laugh:

[Black Yaris]

Umm, Black Yaris, what are you trying to show with those 3 links? I don't see what information they contain that you are trying to convey.

One just apes the old adage about following the vehicle manufacturer's recommendation, another says people don't check their tire pressure, and the last doesn't say anything except it provides a shamelss plug for Bridgestone who, of course, would much prefer you run your tires ragged in 20,000 - 30,000 miles rather than 85,000+.

If I missed anything there feel free to correct me.

do you know how to read? those links say use the tire pressure provided by your vehicles manifacture. Many Bridgestone tires are rated well above 80k miles BTW, same goes for Michelin. the one link was from the rubber manifactures accoc of america, mabe you should read into that site a bit and you could learn a thing ot two about tires. I ain't just pulling shit out of my ass I have gone to training coarses from most of the big tire companies, as well counpany training... I would just love for you to pick up a tire guide and read it, so you can learn how dangerous those high pressures realy are.

on a side note, have you ever seen a tire blow up at 60 psi? I have, it ain't pretty, had to rush the kid to the hospitol, and all he was doing was airing up a pass tire over the rec press cause the cust thought it was best, and he was new and did not know any better, and it blew up in his face... kid was fine... but gave us a scare.....

[SailDesign]

Whew! I'm really glad Ken Obenski read the December [above] issue of this newsletter (SPARE TIRE/TANK CAUTION!) and took the time to share his expertise. He's a registered engineer, works in failure analysis, and blew open my eyes regarding tire overinflation hazards. My original fear dates back to a 6-year-old Coyote blowing out a 24-inch bicycle tire. The December newsletter understatement, "The explosive force of compressed gasses (air) is incomprehensible to most of us," is only emphasized by what follows. I expect, if you're like me, by the time you finish his letter (salient points reprinted below), you'll even be afraid to inflate your tires to street pressure!

1. An 8x15 inch trailer tire, load range E, 85 psi rating, blew out a sidewall during inflation. Tire tech was on top of the tire because the safety equipment was not working right. It launched him first, and went through the shop roof. Compressor was set for 165 psi with no regulator between the tank and the tire but 150 feet of 1/2 inch pipe.

2. A 15-inch car tire, 32 psi rating, gas station had a locking air chuck (OS HA required). User did not realize that letting go of the chuck would not stop air flow. The hose blew out, knocked him down and lifted the tire over a retaining wall. Severe head injury.

3. Wheelbarrow tire, 4x8, 32 psi rating, aired up with unregulated hose connected to 100 psi. The rim split in half and decapitated owner.

4. Nearly new bicycle tire, mine, 90 psi rating, blew off rim at 70 psi. Stress in bead wires is 300,000 psi! Tire manufacturer says, "Tires blow off the rim all the time," like it was no big deal. Tell that to my knee.

5. Bike tires are thin-walled but also very small cross section. Thin-wall pressure-vessel design is just a ratio of diameter to wall. Bicycle tires are bias ply, so the cords don't separate as the tire swells, like a radial. (Bill Fragale, Phoenix area, also nailed me on this one.)

6. My tire engineer warns against exceeding sidewall rating by more than 10 percent. Orris says the first thing to fail should be the sidewall. Steel rims are formed from one piece of sheet and will not fail, but some aluminum rims might fail by the flange breaking off. The rim fragment will be a bullet.

7. Air at about 125 psi behaves like pure oxygen! Organic materials can spontaneously com- bust in it. When this happens the gasses expand even more and what you have is a one-cylinder engine with no crankshaft and no exhaust valve.

8. Navy has one serious accident a day from high-pressure air. See 7.

9. Desert temperatures and high altitude can raise tire pressure another 20 percent (pvnrt = pvnrt). See 7.

10. Tires have a warning on the sidewall not to exceed a certain pressure to seat beads. Usually it is less than 125 percent.

11. Most of the tire-explosion problems we have seen are from putting tires on the wrong size rims. There are 15.5- and 16.5- inch tires and rims, that almost interchange with 15, or 16, but will release without warning, at or near rated pressure.

12.Just because you get away with something does not mean it's safe. Safety factor is not there for us to use, it's a safety margin to deal with the unpredictable, like: Suppose your gauge is off, or the tire has latent defects, or they overstressed it in mounting, or in your case, you high center on a rock.

13.The energy stored in your 32- inch diameter tire at 100 psi is 13,000 foot pounds, enough to lift the entire truck 4 feet, or launch tire and wheel at 146 feet per second. That's 12 times the muzzle energy of a .44 magnum! How securely is that tire attached to your truck?


Not sure how else to say this, but... If "Hypermiling" is your sport, don't play it on roads I have to drive onPlease!

[BailOut]

Then stay off my roads, SailDesign, because I call :bs: on your repost. The original writer apparently failed his advanced math classes and has a paparazzi-style penchant for focusing on and embellishing the one-offs.


On a side note it is best to provide a link to your content source.

[SailDesign]

On a side note it is best to provide a link to your content source.

'Pologies for that. Here she is.
http://www.4x4now.com/sf1296.htm
I have to admit that the "Ecological 4x4" title is a bit of an oxymoron, though :smile:

Looking again at thet "Hows and Whys" section of the CleanMPG site, I note a great many of the things that really really annoy me in other drivers being listed as good. Amongst them:
1) Speeding up and slowing down repeatedly (Pulse&Glide). So frikkin dangerous as no-one else on the road knows what you are about to do next.
2) Speeding up on the downhills and slowing down on the ups. I know, everyone does it, but it's another PITA.
3) Drafting. Stay off my tail and I won't practice brake-stands. Honest!
4) Surfing - aka staying in my blind spot when I would like to pass the other idiot on the road.
5) High-lining or whatever (running with your lefthand wheel on the white line and your righthand wheel on the "hump" between normal wheel paths). This si actually described as helping keep others awake! If you expect me to pull out further and sooner to pass you, better wear some ear-plugs. If you are not in your travel lane, then I will let you know. Look up Rhode Island General Law Title 31, Chapter 15, Section 4. OTOH, I'll save you the trouble. Here it is:

§ 31-15-4 Overtaking on left. – The following rules shall govern the overtaking and passing of vehicles proceeding in the same direction, subject to those limitations, exceptions, and special rules stated in this section:
(1) The driver of a vehicle overtaking another vehicle proceeding in the same direction shall give a timely, audible signal and shall pass to the left at a safe distance and shall not again drive to the right side of the roadway until safely clear of the overtaken vehicle.
(2) Except when overtaking and passing on the right is permitted, the driver of the front vehicle on the audible signal of the overtaking vehicle shall give way to the right, and shall not increase speed until completely passed by the overtaking vehicle.

So, if you are hogging the middle of the lanes, and I honk at you, you are required to move out of the way and not speed up until I'm past. I have only tried this on cops I know :smile:

Steve "doesn't need to drive badly to use less gas"

[PetersRedYaris]

Then stay off my roads, SailDesign, because I call :bs: on your repost. The original writer apparently failed his advanced math classes and has a paparazzi-style penchant for focusing on and embellishing the one-offs.


On a side note it is best to provide a link to your content source.

Angry, angry, angry! Why are you so angry? The consensus is, it's just plain dangerous. You don't need to be upset we're not all jumping on your band-wagon.

Question- Is +.5-2 MPG really hypermiling? Maybe call is Goodmiling. I think you need to double your mileage before the word hyper can be correctly used.:smile:

[SailDesign]

Question- Is +.5-2 MPG really hypermiling? Maybe call is Goodmiling. I think you need to double your mileage before the word hyper can be correctly used.:smile:

I think at the +5 mpg stage, it could be called "supermiling", which would bring +0.5 to +2 into the s'miling range. :smile:

Certainly makes me smile

[BailOut]

The term "hypermiling" refers to continually beating the EPA's combined estimate for your vehicle and can involve combining driving techniques with some changes to your vehicle (including tire pressure). Every additional change you make to your driving style and vehicle nets better MPG, and it all adds up.

The original combined EPA estimate for the Yaris is 37 MPG (it's only 32 under the cheesy new system). My last tank was 49.74 MPG (click my signature for more information) and I commute over a mountain 5 days a week.

By the way, Peter, I'm not angry. Disappointed at the lack of understanding and exasperated with some of the attitudes perhaps, but not angry.

[PetersRedYaris]

By the way, Peter, I'm not angry. Disappointed at the lack of understanding and exasperated with some of the attitudes perhaps, but not angry.

OK, my bad.

I looked at your signiture. You drive 27 mile trips at 41-45 MPH, no wonder your mileage is so high. Drop the E10 fuel and use 100% gasoline and you could do even better.

[BailOut]

OK, my bad.

I looked at your signiture. You drive 27 mile trips at 41-45 MPH, no wonder your mileage is so high. Drop the E10 fuel and use 100% gasoline and you could do even better.

The trip distance includes 16.5 miles of climbing 4,500 vertical feet on the way to work and 7.5 miles of climbing 2,500 vertical feet on the way home. The mountain road peaks at 8,900 feet, has several low-speed cutbacks and is crawling with tourists.

That is my average speed between city, highway and mountain driving. If you track your own average speed using something like a ScanGauge I bet yours would be about the same. Most folk's average speed numbers are between 35 and 45 MPH.

Don't forget that it takes 3x the fuel to climb a mountain as it does to drive on a flat surface, and that I can't make up all of that fuel on the way back down. Trust me, the mileage numbers I'm turning out do not happen by themselves and would be much, much higher if I had a climb-less commute at a lower altitude.

As for the E10 fuel I do not have the ability to drop it. Nevada, like California, uses E10 all year round with a special winter reformulation of it between 10/1 and 1/31 every year (which drops our MPG even more). My Yaris has never known straight gasoline so I wouldn't even know what to expect from it.

[BMGYaris]

so wait a minute. EVERYBODY is in agreement with going over toyota recommendations?

[AaronATL]

use nitrogen at 35 psi, keeps it from expanding to much

[BailOut]

BMGYaris,

Yes. Everyone pretty much agrees that max sidewall is a good thing. The only thing that is being debated is pressures above max sidewall.

[PetersRedYaris]

use nitrogen at 35 psi, keeps it from expanding to much

Good call. Running higher pressures with nitrogen would be safer. Also, driving at altitude yields better mileage due to the lower oxygen content in the air. Keeping air/fuel ratios optimum, less oxygen = less fuel going into your engine. When traveling in the Rockies in Colorado in my Tacoma, I consistently got the best mileage I ever recorded in 90,000 miles of driving. Less power on those passes, but wicked good mileage.

[BMGYaris]

BMGYaris,

Yes. Everyone pretty much agrees that max sidewall is a good thing. The only thing that is being debated is pressures above max sidewall.

Only problem i can see with that is like they mentioned before, as you drive and things heat up the air pressure increases. That means that if you fill to max, then in fact you are driving over max. So being that the factory max. is "maximum safe pressure" (per whoever it is that decided it should be printed there) then actually our max fill up should be well under that....35, 40? to allow for increase in pressure and to still maintain under the maximum?

[PetersRedYaris]

Only problem i can see with that is like they mentioned before, as you drive and things heat up the air pressure increases. That means that if you fill to max, then in fact you are driving over max. So being that the factory max. is "maximum safe pressure" (per whoever it is that decided it should be printed there) then actually our max fill up should be well under that....35, 40? to allow for increase in pressure and to still maintain under the maximum?

Tire companies account for that. The max pressure is a cold pressure.

[BailOut]

Only problem i can see with that is like they mentioned before, as you drive and things heat up the air pressure increases. That means that if you fill to max, then in fact you are driving over max. So being that the factory max. is "maximum safe pressure" (per whoever it is that decided it should be printed there) then actually our max fill up should be well under that....35, 40? to allow for increase in pressure and to still maintain under the maximum?

There is no need to concern yourself with allowing for an increase in pressure. The industry standard for pressure measurement is that it be done when cold (meaning the vehicle has sat still for at least 3 hours, and that the measurement has already taken road use heating into account), so the max sidewall rating on the factory tires is 44 PSI cold.

Just let your vehicle sit still for a few hours and then fill 'em up. If you need to drive to a place to fill your tires then run around for a while so they get good and hot and then fill up at your goal - 5%. For a max sidewall of 44 PSI this means a hot fill to 42 PSI.

[Moose]

I cannot believe that I am reading this- crazy is all I can say.

Listen, I won't list all of the automotive-industry reasons why not to do this, as they have already been listed in one form or another.

I will say this, though- one of the wheeled vehicle maintenance men for my battalion was killed in Iraq when he overinflated a Humvee tire. The tire blew apart and, literally, took the top of his head off. The Army has instituted "tire inflation cages" for this reason alone. Humvee tires are alot tougher than the POS Bridgestones on these cars, too.

I think it is rediculous that you would want to risk your life and the life of others around you for a few miles per gallon.

[BailOut]

*shrug*

You can find a horror story about anything.

We all know higher speeds are dangerous and we've all seen the occasional photographs and videos of spectacular accidents but most folks speed every day, and I bet most (if not all) of the people railing against me are full-time speeders.

My point is that a few of you silly folks act like those of us using higher pressures are driving around on time bombs just waiting to explode, or that we're putting ourselves in mortal danger every time we top off the pressure, when neither is even close to the truth. Again, we represent over a million road miles and countless tire fills/repairs without a single incident.

Again about the automotive industry...

I don't know how many other ways I can say this but they are the absolute last people you should go to for information like this. It is directly against their economic interests both for you to get better mileage and to get longer life out of your tires. Going to them for advice on this is like asking a drug dealer for advice on crack usage.

[brickhardmeat]

MURDERERS

TIRE PERVERTS

[deebrown]

well, the main reason i started this thread was to see if the max tire pressure would improve the stability of my yaris sedan on the highway. I just tried 40 psi (the sidewall of the tire says max is 40) and I noticed a BIG difference in stability at 75 mph...I am beginning to think that the main culprit in the yaris' poor highway stability is the very narrow wheelbase and that this can be compensated for by a strong/max sidewall on the tires - i think i am going to try 44 psi given that the max pressure found at the below link says 44:

http://www.tirerack.com/tires/Spec.jsp?make=Bridgestone&model=Potenza+RE92

[Moose]

*shrug*

You can find a horror story about anything.

We all know higher speeds are dangerous and we've all seen the occasional photographs and videos of spectacular accidents but most folks speed every day, and I bet most (if not all) of the people railing against me are full-time speeders.

My point is that a few of you silly folks act like those of us using higher pressures are driving around on time bombs just waiting to explode, or that we're putting ourselves in mortal danger every time we top off the pressure, when neither is even close to the truth. Again, we represent over a million road miles and countless tire fills/repairs without a single incident.

Again about the automotive industry...

I don't know how many other ways I can say this but they are the absolute last people you should go to for information like this. It is directly against their economic interests both for you to get better mileage and to get longer life out of your tires. Going to them for advice on this is like asking a drug dealer for advice on crack usage.

Well I'm glad you can just shrug off someone's death. Sleep well tonight.

Also, you should keep in mind that it is against the tire and auto manufacturer's economic interests to have tires blowing and customers killed.
But, since you're such an expert, you probably already knew that.

You are driving around with bombs waiting to explode, and one day, it will happen. There are Darwin awards for a reason- "brilliant" ideas backfire all the time. But, don't worry, I'll shrug for you.

[SailDesign]

My point is that a few of you silly folks act like those of us using higher pressures are driving around on time bombs just waiting to explode, or that we're putting ourselves in mortal danger every time we top off the pressure, when neither is even close to the truth. Again, we represent over a million road miles and countless tire fills/repairs without a single incident.

BailOut, my personal beef with this over-pressure thing is that you are actively recommending it here. There are those who will read this ("I saw it on the Internet so it MUST be true") and go ahead with 60psi on a 44max-rated tire. If they get hurt, or worse, it will be because of something YOU recommended. There are numerous documented cases of people being injured by over-inflating their tires.

Sleep well.

[BMGYaris]

lets stop making trite comments like "sleep well" guys. I am sure he will.

One important thing to remember though Bail out, is that people that join websites and groups to make extreme efforts at improving mpg are probably doing alot more than just pumping their tires to 60psi. Those that go to such lengths as to join a group and pump tires 50% over factory specs are probably doing just like you--driving 40mph, checking tire pressure and conditions regularly, and keeping excellent overall care of their vehicle. They probably are more attentive on the roads also, making sure to avoid potholes (which we all do, but I imagine you take it to another level) and other undo stress that might be place on their vehicle. under those excellent conditions i can imagine that nobody in the reported groups would have many problems with blowouts.

(though there is a possibility that when they do blowout they blow hard and so all those members that did have problems died, but we will assume that isnt the case).

However, get ignorant people like myself pumping up their tires to 60PSI and averaging 80-90mph and you have a totally different situation than averaging 43mph.
I don't know much, like I said, but i am inclined to say that going 40mph at 60psi and hitting some small bumps would be a small issue, but travelling 90mph at 60psi and hitting some small bumps overtime might become a major issue. but even without the bumping factor that i just used for an example scenario, the different speeds and driving styles creates a totally different situation--perhaps making your advice very dangerous to the average ignorant fool like myself.

[BailOut]

If you are driving 80-90 MPH you are already in much more danger than anything to do with your tire pressure and you obviously don't care one bit about fuel efficiency or emissions so you would have never gone to 60 PSI to begin with. :laugh:

If you are *averaging* 80-90 MPH then you're not in a Yaris. Hell, you're not even in the U.S.

Your average includes 0 MPH at stop lights, stop signs, etc. It includes 25 MPH through your neighborhood. It includes 35 MPH on avenues. It includes acceleration and deceleration times, etc. To average 80-90 MPH on a commute you'd have to be doing around 225-250 MPH on the highway sections. :wink:

[eTiMaGo]

semantics :biggrin:

I think we all agree on this one thing, high pressure in tires and fast driving are not a good combination. BailOut, I think that if you will write more about the subject, please be sure to have a clear disclaimer about this!

[Blenjar]

I was running on 38 psi, after my first maintenance, the guy said to drop it to 30 psi..

Not sure if I felt a difference but w/e

-- Blen

[brickhardmeat]

I read this story once about this guy who wasn't paying attention while inflating his tire. He over filled it big time. It blew up and a piece of the tire hit him in the neck and killed him.:laugh:

[Blenjar]

I think its a good idea for black yars to make a PSI thread...how bout it!?

-- Blen

[BMGYaris]

come on bailout, calm down for a moment. When i said average I clearly meant the speed I am going the majority of the time, which is on the highway. Though it was the wrong term to use, you are correct.
i drive about 2/3 on the highway at about 80mph, in a particular hurry I go faster, and on a long road trip or if I have time I might do about 70. Around here we have long straight stretches of road with no police, its pretty moderate compared to others actually.
i get about 30-32 mpg which is good enough for me- i wouldn't mind going slower but I am always in a hurry to get to school in the morning, and yes I care about the emissions theoretically but i do little to contribute myself.

Now bailout , I know my primary point in my post was clear to you because you are obviously an intelligent person. My use of the word "Average" was inappropriate, true, but the heart of the content is still very valid and very real. If you are driving very conservatively and mainting speeds of under 50mph the majority of time with 60 psi, then the increased tire pressure will be much less likely to cause blow on you than if you are pushing your car hard, regularly maintaining 80 mph speeds and also have such a drastic increase in tire pressure. It may not happen all at once, but over months combining the average American driving style (especially college student driving styles, for example) with the 50% increase in air pressure could certainly cause for very serious tire problems. Though with your driving style that very well may not be the case.
I really have nothing against you but honestly, i know you understood my point and I know you recognize it as true and valid, so I say we look at the heart of a post and only make brief comments on small mistakes eh?

Also i completly agree that doing those speeds are more dangerous than doing 50% of the speed and raising your tire pressure 50%.

Finally, this thread was not about conserving fuel. This thread was about increasing stability--in particular at high speeds. That is why I am interested in it and apparently what the orginal poster is intersted in, so dont lose sight of the orignial focus.

[BMGYaris]

I was running on 38 psi, after my first maintenance, the guy said to drop it to 30 psi..

Not sure if I felt a difference but w/e

-- Blen

Thats what I hate....I get conflicting information from you guys and from tech guys. And then the mentioned tech guy is wrong as well, I dont have it on hand but i think the manual says 32 all around, and then up it to 34 if your doing 100mph? something like that. Anyway, i dont know what to think, i just know my stability and control, in particular at over 70mph speeds, is seriously lacking, and im tired of it! with no money to make upgrades...this is my only real hope...damn it

[brickhardmeat]

Hey, BMG, calm down, -breathe- go get yourself a set of aftermarket wheels and upgrade the tires, you'll feel a difference, for now you'll be alright on what you've got just keep the pressure within a pound or few of what the manual says, that way you won't murder anybody

I think it may be the suspension more than the tire pressure that is truly bugging you. I know I hated the way the car felt stock.




I missed the part about the money. Start saving, this car needs a few upgrades. It's still a great car though.

[Blenjar]

Well I'm running on different rims weight, tires are heavier and stuff...kinda hard...wtf...this wil lbe a lot of work for Black Yaris to compile :p

-- Blen

[BMGYaris]

I missed the part about the money. Start saving, this car needs a few upgrades. It's still a great car though.


Yea, im pretty fking booked up as far as money is concerned....25k debt for school, owe my gf 500bucks my parents 2.5k and im supposed to propose to my gf this summer...fucking ring.....and like I have mentioned in previous post...she is japanese, which means trips to japan...then an international wedding in 1 1/2 years...all on a future elementary school teachers salary...lol i think my car might be stock for a LONG time....lol...well eventually i will deal with the tires and maybe suspension, and one day a nav so i dont get lost traveling with my woman on the weekends..but its not quite time for that yet.....

[AustinYaris]

I think (at least hope) we're all intelligent to make our own decisions on our tire pressure. As a fellow hypermiler like BailOut, I plan to pump my tires to the hypermiling community's recommended tirewall listed max psi. Even though my personal research has shown BailOut's suggestion of 60psi safe, I probably won't pump it up all the way to 60. Although mpg is one of my goals, I also want to maintain a comfortable ride.

It all depends on what you want to maximize... mpg, ride comfort, stability, breaking... And do your own research before making a decision before blindly listening to anything anyone has said on this board.

And no need to make snide comments towards others on the board, especially if you haven't done your research.

Just my 2 cents.

[Yaris Revenge]

I'm not gonna' rag on over-inflation... hypermiling is just plain weird in the first place. Here's my math, please correct me if it's wrong (I suck at math).

Yaris fuel capacity= 11 gallons
Cost of fuel= let's say a nice even $3/gallon
EPA estimate highway= 40mpg
Estimated range for normal driving then= 440 miles
BailOut's range @ 44mpg= 484 miles

BailOut travels 44 miles further on a tank of gas. That's roughly one gallon of fuel he saved compared to a normal driver.

Back to the top, one gallon of fuel costs $3.

Using all the crazy and sometimes dangerous driving techniques that hypermilers use, the driver has managed to save a measly $3 per fillup.

Using this math (which again, could be wrong) I just don't see how anyone can justify dangerous driving techniques. I say drive reasonably and give up one tall (aka "small") Caramel Macchiato from Starbucks. You'd save the same amount. :wink:

~YR

[eTiMaGo]

Well the EPA estimate is very generous, look at the fuel economy thread in the main forum, real-world consumption is probably more like 35MPG. So, it's more of a 100 miles extra compared to the average driver, which equates to almost 3 gallons, so let's say $8 per fillup.

Refill once a week and you're talking about saving up $416 in a year. Not a lot of money to some, but a penny saved is a penny earned to others :wink:

But yeah, that being said, this technique should really be for those who are very serious about squeezing every last mile out of their fuel, especially if they drive very long distances. Needs a very big disclaimer about the downsides of this too :wink:

[eco]

I will never agree with 60 psi on a 44 psi max tire.I will say this,I try to find the exact pressure for stability,comfort and gas savings and still be safe,I use37psi on a 50psi max tire,my temperature may hit 44psi in the course of a 1hour trip,still no where near 50psi for my tire,I have just found this to be the sweet spot for all 3 stab.,com.,gas sav.,.When I was using the the 44psi max tire I used 38psi,that was the sweet spot for my setup,its all trial and error,but never exceed 44psi when tire is checked cold,the tire will hold 44 cold,and can withstand the increase of psi when the tire is heated up.
Remeber folks,there is no tire making procedure that is 100% all the time,if tire is faulty,and you exceed max psi,then you will more then likely have a problem,think about it.

[Nimble]

Tires are not meant to be run at MAX PSI! Are you kidding me? Seriously, the poster saying he runs SIXTY LBS has got to be kidding. 34 tops on most passenger tires, and 40 on very low profile ones.

[BMGYaris]

EPA estimate highway= 40mpg


Using this math (which again, could be wrong) I just don't see how anyone can justify dangerous driving techniques.

~YR

Hey, well first off I wanted to say that while I do not condone the hypermilling techniques.
Nontheless. The risk of overinflation are pretty simple, and if you do a search around the internet you will find that it is not nearly as dangerous as underinflation. The risk of overinflatoin, as best I can tell are :

1) The thread in the center of the tire will wear out more quickly
2) That it will puncture a bit easier
3) Once the threads are worn down it will puncture much more easily.

Now, because of his hyper milling attitude he has changed other things as well:

1) he tries to maintain about 48mph, or so i hear, and even slower
2) he plans ahead, watches traffic, and is constantly aware of obstacles, pot holes, and general hazards--he takes driving seriously, not fucking around.

I dont have any statistics, but im pretty sure that by cutting back on his speed so drastically and by having his extra care attitude and concern for cautious, intelligent and safe driving on the road--the very concern that caused him to pump up his tires--will in fact make him and everyone else around him much safer. If you had the percentages I am sure that he averages out to be a much safer driver than myself and every other person I know, just based on increased risk of tire blow outs and decreased risk of highspeed crashes.

However, there is another major increase in safety, there is no doubt in my mind that this mother fucker checks his god damn tires every fucking morning. You wont find him without threads on his wheels--but you might find me. You wont find him underinflated--but you might find me. And most people--but not him, because of his overinflation, and his general attitude, I am sure he is much safer and his car is in prestine condition. I think---but i cant find any actual stats or solid information on overinflation--everything focuses on underinflation. still, that is based on what i have gathered thus far, and it seems reasonable.

[BMGYaris]

I'm not gonna' rag on over-inflation... hypermiling is just plain weird in the first place. Here's my math, please correct me if it's wrong (I suck at math).

Yaris fuel capacity= 11 gallons
Cost of fuel= let's say a nice even $3/gallon
EPA estimate highway= 40mpg


~YR

_______________

As for your numbers, new EPA ratings put the yaris at 36 highway and 32 combined
http://www.fueleconomy.gov/feg/calculatorCompareSideBySide.jsp?column=1&id=22750

That means that if our man is using highway figures it is just as the frenchman prooposed, and if he is giving you combined then it is even better. Also, but it in terms of hours worked. if he can save 9 bucks at the fill up, thats going to be more than 1 hour of work saved per tank, which is significant (for me as a student I only make 7 bucks an hour:), you can figure out your own).


But, and i think you will like this one if your with me, Say at EPA ratings at 11 gallons with 36mpg, we can drive 396 miles per tank right? now (lets just say we are doing the whole tank on the highway since we are using the highway EPA figures) so we average 80mph. At 80 mph it will take us 396/80=4 hrs 57 minutes. Now if he averages 50 mph it will take him 396/50=7hrs 55min.

He lost three hours, and he still has 2.9 gallons of gas left, around here that is about 9 bucks, and my 1 hour is usually worth more than 3 bucks to me so in my mind, that isnt worth it. Of course, in a heavy commute is when I imagine his numbers shine the best because they will usually take the same time, but you can work those out on your own, im tired of this now:)

At any rate, i think he is probably balancing it out more than equally wherein safety is concerned.

[Yaris Revenge]

Yeah, I agree BMG. I'm not crazy about the over-inflation, but that part isn't really what concerns me so much about hypermiling. The techniques that I find more worrisome are speeding onto downhill offramps/onramps to maintain momentum, drafting (aka tailgating!), killing the engine while running downhill (which kills power brakes and steering on most cars), etc. That just seems a little crazy. :biggrin:

I fully expect that later down the road hypermiling will be recognized as a disease, like alcoholism, that affects addictive personalities. Some people can get into it and have a little fun, but know when to quit, while others go totally insane, like that other guy mentioned in the article. I've read about him before... never runs AC, actually pushes his car out into the road to save that extra 20 feet, etc. :laugh:

~YR

[BMGYaris]

hum, i think at that point its obviously not financial. But if it was a matter of envrionmental concerns then surely other things that he is doing in his life have such a greater impact on the environment that those 20 feet are completly irrelevant. so i figure it cant really be about environmental concern or he would be out living on horse back and nature...i wonder what other motive it could be....

[AustinYaris]

BailOut's range @ 44mpg= 484 miles

BailOut travels 44 miles further on a tank of gas. That's roughly one gallon of fuel he saved compared to a normal driver.

~YR

YarisRevenge,

Just a quick note: BailOut has improved his MPG to 49 lately. 44 is an average of all his tanks from the very beginning.

There are lot of more skilled hypermilers who get 59MPG on a regular gas ACCORD for example. So there's actually LOTS of room for improvement on our Yarises.


Also a note on hypermiling... yes, I agree with you guys. Some of the techniques are not very safe...hypermilers are aware of this, and we'd be the first ones to admit it. But I would have to say it's still much safer than people driving while talking on their cell phones.

Also, at least for me, I don't do "all this work" to get save just a couple of bucks. I really enjoy it more as a hobby, a sport, the challenge of trying to reach 50+mpg.

[BMGYaris]

WELL, maybe not talking on the cell phone...but a few days ago I was browsing the internet on the interstate....maybe yes on that.

oh, and is not talking on the cell phone part of hypermilling techniques?

[PetersRedYaris]

I cant find any actual stats or solid information on overinflation--everything focuses on underinflation...

People fail to maintain their cars properly ,including tire pressure, and this is the reason for the focus on underinflation. If you neglect your tires, eventually the pressure will drop creating a dangerous situation. This is a COMMON problem. Overinflation is not a common problem as tires do not spontaneously jump up in pressure. Someone has to overinflate them on purpose. I'm sure after this "hypermiling" trend becomes more well known, and a few 60 PSI tires blow violently causing mayhem on the freeways, the danger of overinflation will spark a few tire pressure studies focusing on overinflation.

[Nimble]

People fail to maintain their cars properly ,including tire pressure, and this is the reason for the focus on underinflation. If you neglect your tires, eventually the pressure will drop creating a dangerous situation. This is a COMMON problem. Overinflation is not a common problem as tires do not spontaneously jump up in pressure. Someone has to overinflate them on purpose. I'm sure after this "hypermiling" trend becomes more well known, and a few 60 PSI tires blow violently causing mayhem on the freeways, the danger of overinflation will spark a few tire pressure studies focusing on overinflation.

99% true, but tires do increase pressure on their own as temps increase (you probably already knew that). I've heard that for every 10degree F increase, the tire pressure goes up 1 lb.

[Nautical Yaris S]

personally, i wouldn't put my tires past 45psi.
especially since I live in the valley where the temperature gets to 114+ degrees all summer long.

[PetersRedYaris]

99% true, but tires do increase pressure on their own as temps increase (you probably already knew that). I've heard that for every 10degree F increase, the tire pressure goes up 1 lb.

Exactly, I should have included that.

[PetersRedYaris]

This has been stated before, however, people keep making posts about the tires increase in temperature leading to over MAX pressure recommendations. The max pressure written on the side of the tire is a COLD max pressure. So, if it is 45PSI max, the tire manufacturer knows the tires will heat up thereby increasing the pressure above the max. This does not mean you have to calculate the real max pressure based on your local driving conditions and temperatures. It is recommended you check or adjust tire pressures in the morning before any substantial driving. You can set it at 45PSI. Yes, it will go above 45PSI when you drive fast or as the day gets warmer but that is already figured in.

[marcus]

i got front tires on 44psi and back tires on 40 psi .. thats if the air pump pressure meter really is accurate..

[Pavel Olavich]

I'm not gonna' rag on over-inflation... hypermiling is just plain weird in the first place. Here's my math, please correct me if it's wrong (I suck at math).

Yaris fuel capacity= 11 gallons
Cost of fuel= let's say a nice even $3/gallon
EPA estimate highway= 40mpg
Estimated range for normal driving then= 440 miles
BailOut's range @ 44mpg= 484 miles

BailOut travels 44 miles further on a tank of gas. That's roughly one gallon of fuel he saved compared to a normal driver.

Back to the top, one gallon of fuel costs $3.

Using all the crazy and sometimes dangerous driving techniques that hypermilers use, the driver has managed to save a measly $3 per fillup.

Using this math (which again, could be wrong) I just don't see how anyone can justify dangerous driving techniques. I say drive reasonably and give up one tall (aka "small") Caramel Macchiato from Starbucks. You'd save the same amount. :wink:

~YR

YarisRevenge, your math has a BIG FLAW....you make the mistake of using the EPA 34/40....what you should have done was use real world, what most people get driving "normall"....which is more like 25/34, and not 34/40, so if you correct your math, then the savings is a hell of a lot more then $3/tank full, and this savings adds up over many many tank fulls. The actual savings is more like $7.50+ per tank full. Over a years time, you will save a lot of $$.

Did you go to college?!? BailOut is doing the right thing, and there is vertually NOTHING inherently dangereous about most hypermilling techniques.

[TLyttle]

Yeah, me, too. In the old days, radials got better mileage at high pressures (smaller contact patch), better traction at lower pressures (larger contact patch). I cannot assume that the logic of this has disappeared, but I have seen no major changes in tire technology that would challenge it. I used to dump my Michelins down to as low as 15lbs for heavy snow conditions, and went where no snow tire would go!

The smaller contact patch, however, generates less heat, so it is possible that lower pressure only benefits the tire companies. I also found that higher pressures had more sidewall stability ("creep"), and gave more precise steering.

But that's just my experience; I was running radials before they were even legal in some states!

[reznunt]

damn 60 psi, it must feel like you're driving a damn tank to work.

[Black Yaris]

ok out of control, and not worth debating and fighting over AGAIN!!!... done