Correct Tire Pressure?

[Rick Ohnsman]

As are most of us, I'm trying everything I can to wring the most mileage out of a gallon of gas. I know tire pressure is important (and about the cheapest "fix") to getting good mileage. But what's the right pressure?



I'm running the tires that were on the truck when bought used from the dealer - El Dorado XTR Sport - P255 70R16. The little web research I've done on these indicates they are probably made by Cooper Tire and sold through Walmart. (Figures that the dealer probably put something cheap on to sell the vehicle). They seem to be getting the job done though.



I'll be darned if I can find anything printed on the tires themselves about proper pressure. I did note a little decal however inside my fuel filler door that shows for this sized tire (which must be the "stock" size for an ST??), that 30 psi for the fronts and 35 psi for the rears is recommended. That seems a little high to me.



So... what is the "proper pressure" for these tires to get the best fuel economy, ride, and tire wear?



- Rick

 

[P M]

All tires should have their max pressure indicated in small print on the sidewall. :unsure:

 

[Byron Pletcher]

wear and economy tend to be different





for me even wear tends to be around 32 front and 31 rear.



economy; i run the fronts at 34 and rears at 36.







to see if your tires are at correct pressure for even wear, draw a line in chalk across the tread and drive a few feet and keep checking / adjusting the pressure to have the chalk disappear at an even rate.

 

[Dreman]

I'm running 40 front and rear, but my tires list the max pressure on the sidewall as 44 psi.



It has to be on there somewhere, but maybe it's on the other (inside) side. It'll say something like "Max loading is 2,038 lbs at 36 psi max pressure". Your numbers will be different, but the wording is usually similar.

 

[EddieS'04]

When I had that size, I ran 35 on all 4....

 

[Rick Ohnsman]

I stopped at my local tire shop, Les Schwab, over lunch and had them look at the tires. Sure enough, in tiny type it said that the maximum tire pressure should not exceed 35 psi... which.. was what the guy said the tires should be filled to. (???) 35 psi doesn't sound too high, but filing to the maximum??? What's with that? :blink:



I know these are probably cheap tires, but filled to 35 psi I can feel every tiny bump in the road. Does this seem right you you?

 

[Yardsale]

Seems a bit high, at least for my taste. Try 32 front, 31 rear and see if you like that.



I like Byron's chalk test - simple and probably works well.



Another "trick" (for the anal retentive) is to measure the radius of each wheel from the ground to the center of the rim (actually, since the rim diameter won't change with different inflation pressures, you can measure from the ground to the bottom of the rim). This will insure that each tire is inflated to the same running diameter, which may be different inflation pressures in each tire. I've not tried this, but it's interesting.