I have a Jeep Wrangler. The manual gives 33 psi as the recommended cold inflation pressure for all four tires. Over the years, I have usually kept my tires a little over the manufacturer's recommendations. In the Jeep's case, I usually inflate them to 35 psi.

I just noticed that its current tires, Goodyear ArmorTracs (P255/75R 15), have a max pressure of 51 psi indicated on the sidewall.

Long ago, I read an article in Road & Track that there is no harm in inflating tires to their max, except the ride will not be as soft. The vehicle's mpg will improve, as will braking, handling, and tire life. There was a caveat that if there is a difference in pressure front to rear, then that difference should be maintained.

Going from 33 psi to 35 psi is one thing, but I am wondering if it is advisable to go all the way to 51 psi. Anyone have any opinions?

John, I have a Wrangler and the tire pressure monitor shows that my tire pressures can rise 5-6 degrees after driving for 10-15 miles, so you wouldn't want a cold inflation near the maximum.

Additionally, keeping them at maximum will likely result in excess wear down the middle of the tread.

I keep mine at a cold 36-37, which means in winter that I have to add a few pounds as the cold weather causes lower inflation.

Totally unnecessary and potentially bad for your suspension. Follow the mfg pressures, not the sidewall max. Totally different calculations that have nothing to do with each other.

-Rob

You are seeing the max allowable pressure for the tire, not recommended pressure for the vehicle. Although there can be times to alter a bit from the mfg specs, 51 is CRAZY for your vehicle, not to mention terrible center wear, and poor performance of the tread.

Thanks for the good responses. I was leery of going to the sidewall max in this instance.

I would maybe go as high as 39 lbs. BUT, no way would I put 51 psi in them. Higher pressure will give you less traction and poorer stopping (35-38 psi shouldn't effect things too much) as well as a stiffer ride that might be unsettled easier losing control sooner in various scenario's......You should get better gas mileage but that's about it.

My 4600 pound truck I ran the OEM 245/70/17 tires at 36# until some tire shop guys said 40# is preferred. Living near a pot-holed area, the ride is a trade-off against blowouts. As they heat, 44# may be hit.

The other reason I ride high is that one of them has a super-slow leak on a plug, and I like some safety margin between replenishing air.

Getting a new pair of tires soon, and the other new pair a couple months after that. Unless they go on sale.

I put 120 miles/day on my daily driver, Olds Intrigue, running on Michelins. Kept the tires cold at 40psi put 253K miles on the car without issue. However, with a cheaper brand of tires it didn't work so well.

My GMC 2500HD diesel tips the scales at 8,800lbs and I run it with 60psi up front and 40psi in the rear. They are supposed to be at 80psi according to GM, but that will beat the snot out of you on the highway when unloaded. The truck ran me much smoother with a few thousand pounds in the bed.

For normal driving, I keep my Wrangler tires between 37-40 psi.

32-35 for most cars.
50 in the 10-ply, E-rated truck tires.

Usually 2 or 3 lbs over the door sticker

The whole concept is putting the width of the tread against the ground for traction and control. Put a chalk line across the tire, drive it around the block, then come back and look at it. The amount of chalk worn off is the area of tread actually contacting the road.

Believe it or not car and tire manufacturers pay engineers hundreds of dollars a month to come up with the numbers they publish.

I run 36F/34R in my Dakota quad cab and keep a pretty well balanced tread wear. I arrived at these pressures after watching my tread wear, wear in the center = too much press, outer tread wear = not enough pressure.

Optimal tire pressure is effected by vehicle weight. A few extra PSI will like not hurt anything. I would put 50 psi in a vehicle that recommends 33psi.

To much and you could see excessive wear in the center of the tire vs. the sides but you would really have to go past the vehicles recommendations.

I don't like under inflated tires and will take over inflated any day but within reason. To high can effect cornering and even breaking we are talking about at the extremes to see much real world effects.

The number on the sidewall is to carry the maximum load that the tire is rated to carry.
I've run mine at the max for decades and the only issue is potential higher wear in the center and a harsher ride.
The max pressure is NOT a safety issue. The tires could run much higher than that without a problem. Running pressures too low is much worse and is a potential safety issue.

quote:

Originally posted by Alpine79830:
The whole concept is putting the width of the tread against the ground for traction and control. Put a chalk line across the tire, drive it around the block, then come back and look at it. The amount of chalk worn off is the area of tread actually contacting the road.

This is the best advice, and what I do with every vehicle. Chalk (blackboard chalk) across the tread, then drive it a few hundred feet on pavement. You will easily see where it is wearing. If it wears on the outside, decrease the pressure, if on the inside only, increase the pressure. What you want is an even wear mark in the chalk across the entire tread.
 
That will be your ideal pressure for that tire, and that vehicle. I usually put a sticker in the door jamb with the "correct" pressures.
 

quote:

Originally posted by henryaz:

quote:

Originally posted by Alpine79830:
The whole concept is putting the width of the tread against the ground for traction and control. Put a chalk line across the tire, drive it around the block, then come back and look at it. The amount of chalk worn off is the area of tread actually contacting the road.

This is the best advice, and what I do with every vehicle. Chalk (blackboard chalk) across the tread, then drive it a few hundred feet on pavement. You will easily see where it is wearing. If it wears on the outside, decrease the pressure, if on the inside only, increase the pressure. What you want is an even wear mark in the chalk across the entire tread.
 
That will be your ideal pressure for that tire, and that vehicle. I usually put a sticker in the door jamb with the "correct" pressures.
 

You have it backwards...if the chalk shows center wear only, reduce the pressure. Edge wear only, increase the pressure.

quote:

Originally posted by mo4040:

You have it backwards...if the chalk shows center wear only, reduce the pressure. Edge wear only, increase the pressure.

That does not surprise me (that I described it backwards), and you are correct. But put me out there with a piece of chalk, and I will get it right
 

With respect I think your increase/decrease is backwards but in regards to the OP it comes down to the individual driving the vehicle, what do you want? My XJ goes from 12 psi off road to 34 on the road, it's up to what the driver wants to do.

quote:

Originally posted by henryaz:

quote:

Originally posted by mo4040:

You have it backwards...if the chalk shows center wear only, reduce the pressure. Edge wear only, increase the pressure.

That does not surprise me (that I described it backwards), and you are correct. But put me out there with a piece of chalk, and I will get it right
 

Dang Henry, is this the cause of the chalk shortage in the SW?

(Edited to add emotion)