Tire pressure?

[otterhere]

So where do you guys keep your tires for best MPGs? I figured unless the alarm came on (warning system), they were fine, but now I'm wondering...

[YAR1S]

.... I personally set them to 32.... just cause I dont want to be on the end of a lawsuit... resulting from a crash that could be attributed to traction loss on my part.


Besides... from what I've heard the differnce isnt much... give or take a few miles, right?

[BailOut]

Increasing tire pressure increases handling, traction and tread life as well as mileage. I run mine at 60 PSI, as do thousands of other hypermilers.

Originally Posted by YAR1S

Besides... from what I've heard the differnce isnt much... give or take a few miles, right?

Fuel efficiency is all about many tactics adding up to significant gains. Tire pressure is one of the larger factors.

[YarisSedan]

=>

[YarisSedan]

I think the max for a small passanger car tire is 50psi tops. Also the reason why you get better gas milage is becuase now you have less tire to pavement contanct resulting in less rolling resistance. But in turn you will wear out the center of your tire very quickly. There is also a reduction in traction after you get past a certain point of overinflation. Which randomly guessing would be around 45. As well as greater chance of damage to the tire from potholes and road debri. Also depending on the weather climate where you live and the speeds you are going the heat will cause the air in the tire to expand by a few more pounds. Just like when youloose a few pounds of air in colder climate. This could result in psi ranges of 65. Only tires i know that are meant to be run at those raitings are the huge truck tires.

If you want to get the best economy with handling inprovements without and risk or increased wear on tire i would set it around 40. But definately not in the 60s.

[PreciousPups4U]

Mine are around 40 - 42 psi. That rides best to me. Not sure how it affects mpg, it's just what's comfortable to me. I can really tell when they get low.

[*MAD DOG*]

Originally Posted by BailOut

Increasing tire pressure increases handling, traction and tread life as well as mileage. I run mine at 60 PSI, as do thousands of other hypermilers.

Fuel efficiency is all about many tactics adding up to significant gains. Tire pressure is one of the larger factors.

Too high. You'll have a blowout on a hot day. Your tires are a ticking timebomb.

Originally Posted by PreciousPups4U

Mine are around 40 - 42 psi. That rides best to me. Not sure how it affects mpg, it's just what's comfortable to me. I can really tell when they get low.

That's what I run mine at and that is the maximum the handbook recommends. I feel that 40-42 psi is perfect.

[4MPG]

Originally Posted by BailOut

Increasing tire pressure increases handling, traction and tread life as well as mileage. I run mine at 60 PSI, as do thousands of other hypermilers.




Fuel efficiency is all about many tactics adding up to significant gains. Tire pressure is one of the larger factors.

more pressure may increase mileage, but it sure as hell doesn't increase handling/traction or tire life.

your getting better mpg because you have less tire contact on the road (less resistance) and less flex (wasted energy). However, this also results in less traction and poorer handling. It will also reduce tire life by wearing the center tread faster, since it takes all the wear instead of spreading it over the entire tire... you will get a bald center with tread still on the sides. You can see a picture of this at almost any tire store, as they usually have them posted up along with the reason for it happening and what causes it etc. While overinflation might result in a drop in tire temp, the center wear will outweigh any benefit.

If you want even more proof, especially on the traction side, visit any local dragstrip. You will see all of the "street" cars lowering tire pressure after they arrive, and almost any dragstrip worth its salt has a compressor so you can bring them back to road pressure before you leave. The drag radials on my mustang are particularly sensitive to tire pressure, going from 25 to 20 PSI resulted in nearly a .2 second faster 60' time. Even on my buddies T/A, with stock goodyear regular radials, he was regularly picking up .1 in the 60' with a 5-8 PSI drop from his street pressure.

For traction, and to a lesser degree handling (gotta keep the pressure up enough to keep the sidewall fairly stiff) you want a lower than standard pressure, not higher. You want as much resistance as possible, as resistance is what gives you traction/handling, and to achieve this you get as much contact patch as you can. The basic idea is to lower the pressure to the point that you have as much of the outer part of the tire in contact as possible, without causing the center section to actually start rising from the road (too underinflated).

Edit: To answer the poster above me, to get maximum tire life your probably going to want to run your tires a few (3-5) PSI higher than the doorjam recommends. The doorjam takes into account the best PSI for the tire, but it also takes into account that a lower pressure will result in a better ride (soaks up more vibration/bumps etc).

[50MPGDream]

over 22,000 miles logged on the stock tires at 50 PSI

and for the record, i once had a blowout in my camaro on a tire that was less than a week old with the PSI at 32... not all blowouts are related to PSI, and I think it's safe to say that it had nothing to do with the PSI but more to do with whatever was on the road that poked the hole in the tire

Originally Posted by 4MPG

If you want even more proof, especially on the traction side, visit any local dragstrip. You will see all of the "street" cars lowering tire pressure after they arrive, and almost any dragstrip worth its salt has a compressor so you can bring them back to road pressure before you leave. The drag radials on my mustang are particularly sensitive to tire pressure, going from 25 to 20 PSI resulted in nearly a .2 second faster 60' time. Even on my buddies T/A, with stock goodyear regular radials, he was regularly picking up .1 in the 60' with a 5-8 PSI drop from his street pressure.

My camaro's best 60' time (1.8xx) came on a set of drag radials at 20 PSI, but that relates to MPG in no way (I'm sure I was using more than a gallon per mile in those 60 feet)

[gid]

33 > 35 p.s.i. . Still averaging in the upper 30's at these settings . Check every week or so due to change in the temps .

[gid]

here we go again ... temps will rise and some will have a blowout .

[b_hickman11]

I run 6 psi....I like to hear that thud a thud a thud sound when I drive!

[Snyprwlf47]

Originally Posted by b_hickman11

I run 6 psi....I like to hear that thud a thud a thud sound when I drive!

ROTFL... Anywho I run 40-42 PSI for mountain racing to prevent tire roll...As a side note most tires have a max sidewall pressure posted on them of about 45-50 depending on manufacturer....They should put crosses on tire pressure gauges at about 55 PSI cause at that point your praying every time you press the gas!!!

[BailOut]

*MAD DOG*, gid, YarisSedan:

Nearly 4,000,000 road miles between folks at CleanMPG, PriusChat and other sites say that you are wrong. My experience and the experience of every other MPG-minded person on this site says you're wrong. The engineers from Nokian that we spoke to about this issue - at length - say you're wrong.

What you three say held true up through the 1980's, but with the move to steel belted radials and modern materials beginning in the early 1990's everything changed. It is time to update your personal stock of information.

[rningonfumes]

60 psi here And did it all summer too.

I think I scared the Good year tire guy when I had to get one of my tires patched...I even warned him a head of time. He got curious when I asked him to leave the psi of the other tire alone, so he checked one of the good ones and found them to be about 75 when hot.

[*MAD DOG*]

Originally Posted by BailOut

*MAD DOG*, gid, YarisSedan:

Nearly 4,000,000 road miles between folks at CleanMPG, PriusChat and other sites say that you are wrong. My experience and the experience of every other MPG-minded person on this site says you're wrong. The engineers from Nokian that we spoke to about this issue - at length - say you're wrong.

What you three say held true up through the 1980's, but with the move to steel belted radials and modern materials beginning in the early 1990's everything changed. It is time to update your personal stock of information.

Originally Posted by rningonfumes

60 psi here And did it all summer too.

I think I scared the Good year tire guy when I had to get one of my tires patched...I even warned him a head of time. He got curious when I asked him to leave the psi of the other tire alone, so he checked one of the good ones and found them to be about 75 when hot.

About 9 years ago I had tires over inflated at 50 psi on a car. It was a hot day around 37c and I was on a freeway doing 100km/h I was going around a bend and I heard a loud bang and thud thud thud thud.

I pulled over to the emergency lane very slowly and braked ever so slowly.
When I got out to examine the damage I noticed the tread had popped off my front left tire, some had wrapped around my steering arm and other wheel related stuff.

The rest had been blown apart and was on the freeway. The tire remained inflated but the tread was shredded and gone. I will not over inflate my tires. 40-42 is the maximum in the handbook, that is only recommended for the rear tires under load, that is as far as i will go.

If your suicidal and want to have your tires running between 60-75psi go ahead. Just tell your loved ones that you love them everyday, as it may be the last time you see them.

[talnlnky]

i try to stay near the upper limits of the sidewall rating on the tires... so...40-45psi for me. Problem is... temps have dropped about 60F over the past 3 months, so it seems i'm always adding air to keep it up.... In the spring i'll have to pay attention to make sure I don't go above 45.

[BailOut]

*MAD DOG*,

Tires blow out due to manufacturing defects or excessively hard driving. It is likely that the one tire you experienced this with one time would have blown out even at a lower pressure.

By your logic someone that had a blowout at the pressure on the door jamb could forever run around claiming that you should run 20 PSI lower than the door jamb.