Tire Pressure Max

[PetersRedYaris]

Originally Posted by BailOut

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]

Originally Posted by PetersRedYaris

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]

Originally Posted by AaronATL

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]

Originally Posted by 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.

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]

Originally Posted by BMGYaris

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]

Originally Posted by BMGYaris

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.j...l=Potenza+RE92

[Moose]

Originally Posted by 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.

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]

Originally Posted by BailOut

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.

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.

[eTiMaGo]

semantics

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!