tire pressures

[colonel6632]

what tire pressures does everyone run. on my winter tires i'd run 40psi with the tire rated for 40psi.

these new tires (allegra fuel max) are rated for 51psi, so i inflated the to 41psi. (canadian tire had them at 30)

what do you guys run?

[jackal2000]

32 all around.

[bentiac]

32 is enough for normal driving and probably the best for fuel economy. 36-40 for performance and you can play around with it to create oversteer/understeer

[Redog]

I try to keep it at 35 all around.

[kwhauck]

i always fill my tires to 5 under maximum rating

[colonel6632]

32 is enough for normal driving and probably the best for fuel economy. 36-40 for performance and you can play around with it to create oversteer/understeer

wouldn't the higher psi technically be better for gas mileage

[TdotAlero]

My winter tires I had them at 30, sometimes even at 28. Now my summers are at 32 all around. My 17" low pros on my Hyundai I keep them at 38.

[That01Olds]

I keep mine anywhere from 30 to 35 psi.

[widbyj]

Steady at 40 but thats on 18" KDWs....

[TheEdgeofSanity]

I keep mine at 32-33 all around...i used to keep my pirellis at 40 psi but they wore badly, making me think the manufacturer suggested psi would be better. no decrease in fuel economy, just a better ride!

[whiterider00]

keep mine at 40. max psi is 44.

[Weazel]

Usually 34-36

[Daytona]

wouldn't the higher psi technically be better for gas mileage
Yes it would be.

Manufacturers' Recommended PSI ratings give the best overall combination of riding comfort, stability, cornering/handling, wear, and fuel economy for that vehicle/tire combo.

Increasing your tire pressure reduces the footprint & rolling resistance of the tires, causing an increase in fuel economy. And it stiffens the sidewalls allowing for faster cornering. Police vehicles routinely overinflate their 32psi tires to 40+ for this very reason (high pursuit driving).

Sgt. Dave Storton, Director of the San Jose Police Academy, recommends that for best fuel economy and handling you should always use the maximum allowed tire pressure printed on the sidewalls of the tire.

He also says that the San Jose police department uses a pressure of 50 psi in the training vehicles even though the maximum sidewall pressure is 44psi. This improves the fuel economy even more than just inflating to the maximum rating.

"The proper tire pressure for the Police Crown Victoria is 44 psi. If you look on the sidewall of the tire, you will see that it lists 44 psi max pressure. Regardless of what vehicle you have, use the maximum pressure listed on the sidewall. Higher pressure results in better performance, decreased tire wear, and it lessens your chance of hydroplaning at a given speed."

Still I don't recommend anyone to use a pressure above the tire maximum as it could put you into unwanted liabilites or give you a leak or blowout if the tire is old.

If you run a tire over-inflated you reduce rolling resistance because you're effectively stiffening and narrowing the tread contact patch. This makes it cut through water better, BUT it also creates a much stiffer ride for you & your passengers and could lead to shortened tire life as you wear out the centers. This is not as important on small width tires, but its very important on a big, wide tire.

As far as I know, using a tire pressure somewhere between the vehicle manufacturers recommendation (which is often in the low end) and the maximum pressure printed on the sidewall of the tire should be safe as long as you are not pushing it with performance, racing style driving.

According to Christopher J. Longhurst of "The Wheel and Tyre Bible" another good starting point for performance driving is the tires maximum inflation pressure minus 10%.

The maximum inflation pressure can be found at the side of the tire. If it says 40psi, use 40 - 4 = 36psi as your starting point.


TIPS:
If you are driving on a sandy beach and get stuck, lower your tire pressure substantially to gain better footing.

If you want to perform sustained stunt driving and ride around on 2 wheels (left or right), increase your tire pressure to 100psi.

[bentiac]

I have to disagree with the higher tire pressure => better fuel economy. To have the best fuel economy you would want the best grip on your tires; if lower you would waste energy with excessive role friction and if too high you will loose energy with the loss of grip.

For every tire there is an optimum point of grip and this point will change depending on your driving style; the best grip in hard corners is achieved by a pressure higher than the optimum pressure for the straight line.

The reason cops have higher pressure is not for fuel economy but for safety of keeping those tires from peeling off when they go sideways. I thought I would upload this nice graph for your viewing:

http://img101.imageshack.us/img101/1015/tirepressure.jpg

[Daytona]

I have to disagree with the higher tire pressure => better fuel economy. To have the best fuel economy you would want the best grip on your tires; if lower you would waste energy with excessive role friction and if too high you will loose energy with the loss of grip.

For every tire there is an optimum point of grip and this point will change depending on your driving style; the best grip in hard corners is achieved by a pressure higher than the optimum pressure for the straight line.

The reason cops have higher pressure is not for fuel economy but for safety of keeping those tires from peeling off when they go sideways. I thought I would upload this nice graph for your viewing:



But your argument against better fuel economy is conflictive to your 2nd sentence. Moving my Alero slightly from 32 to 35 cold psi improved my gas mileage by 2-4 mpg (depending on mix of local and highway driving) for the same routes.

Mftr Suggested psi is a compromise of ride comfort, etc. as I stated above in my previous post. You can gain some efficiencies in fuel economy by raising it a certain amount over the recommended pressure. Under normal driving conditions, it's when you go too high over the recommended or even the max. that you start to start a dimishing rate of return on mpg.

And in case anyone was confused, Sgt Storton does not worry that much about fuel economy in his pursuit vehicles. He's more concerned about keeping the cars stable at high speeds, especially in cornering. He has noticed some increase in gas mileage, though, when drivng at normal (posted) speeds with tires inflated past 40.

[bentiac]

Daytona, I agree. We seem to be saying the same thing: that there is an optimum point for the best fuel economy. Where that is will depend on the individual.

As in your example it's around 35 PSI and that's probably because you have softer tires (lower UTQG) or drive harder around the corner. 32 PSI seems to be the magic number for the average driver with the average tire on the average car.

[zzyzzx]

On a front wheel drive car I always put more in the front than the back, and usually more than what the sticker on the door says. My main motivation is that I want to make sure I never go below the recommended value, even if I don't check it again for another 2-3 months.

[JLw7123]

i keep mine at 40PSi on my 18s