75psi tire pressure OK? (unloaded)

[DennisG01]

Just wondering about this - not worried about ride quality - just looking for the best MPG I can get. Is it OK to run 75PSI in the tires when unloaded? Or, will this cause the center portion of the tread to wear faster? I don't tow anything over the winter, so the tires will be pumped up for a few months and this is my daily driver.

[DA BIG ONE]

Need to see how much thread is on the ground at that pressure.

Chalk, works somewhat, but a water based paint is better, apply it as a thin line across the thread on all four tires drive around and see how much is left on the tire. You are looking to keep the whole width of the tire on the road.

All tires are different so the above method is about the best method to find that sweet spot.

[DmaxMaverick]

Good advice above, but may only apply to new or like new tires. The inflation had to have been correct (load dependent) for the life of the tire if there is considerable miles on them. Once the tread becomes crowned, the chalk (or paint) method will not be accurate, it will only show the contact area of the current tread wear of the tire.

The fuel you save by running higher pressure may not offset the cost shortened tire life. Saving a penny is OK. Just make sure it doesn't cost a nickel to do it.

[tanker]

For what its worth, the door sticker on my suburban reads 50psi front, 80psi rear. Thats 30psi different from front to rear, but I assume that is for the max load of 8600lbs. I have run 55-60 on all four when not towing, good ride, and don't think it hurts the fuel economy either. I think 75psi is too harsh, but then you did say you didn't mind. smile.gif

[DennisG01]

Thanks, guys. The tires only have a few thousand miles on them so I'll try the paint method. I have been pretty good at keeping the tires properly inflated.

[gkegel]

A piece of Duct tape across the tread from Side wall to side wall and then run it on there for 50 miles and you will see the wear pattern for more diving conditions. It will actually last for 200 miles.
I had a worn trailer tire worn on the outside edge but good tread on the inside so I had the tire remounted the other direction to use the good side. With the tape i could see that the worn side was not even hitting the ground when cornering. The tire lasted another 1500 miles coming down from Alaska Before I changed it.
Good Luck gary

[DennisG01]

Yet another great use for the all-powerfull duct tape! Hey, if I put duct tape over the whole tire, do you think I would never have to buy tires again? ;) tongue.gif

[sturgeon-phish]

Ride withstanding, inflation to maximum pressure marked on sidewall would be OK I'd think. I've noticed different max pressures from different manufactures in the same temp, load and wear range and speed rating. I run mine at the max.
Jim

[DmaxMaverick]

I've noticed different max pressures from different manufactures in the same temp, load and wear range and speed rating. The manufacturers don't determine tire ratings and pressures. USDOT does. If you have a tire that differs from the norm, it is not DOT approved. For a given tire letter/ply rating and size, the recommended pressures will be the same, regardless of the manufacturer. You could have a tire of the same rating, only of a different size, and the capacities will be different. Contact area (width X circumference) and internal volume determine the rating and max pressure for a ply rating. A good example of this is a comparison between a 245/75/16E and 265/75/16E. Both having the same rating, temp, and technology (radial/bias ply), have a significant capacity difference. At 80 PSI, the 245 is rated at 3042#, and the 265 is rated at 3415#. A 285/75/16D is rated at 3305# at 65 PSI.

These numbers are only valid when the tires are installed on the correct, manufacturer-recommended (also a DOT requirement) wheel size. Those who install tires on wheels narrower or wider than what is recommended may have good results, but are voiding the formula by reducing the internal volume of the tire, and operating outside the approved design.