Tire pressure
- Thread starter dynaglideandy
- Start date
By coincidence I was just checking the air pressure on my 2000 Sport with 31X10.5/15's and they read about 27 psi. No complaints about the ride I'm getting so they'll stay that way.
I have been unable to explain why underinflation can cause wear in the middle of the tire., but it does. At a slight level of under inflation in a steel belted radial tire, there is not enough pressure to hold the center of the tire patch against the pavement. It develops a dimple underneath the center of the tire patch. As the tire rolls with this dimple, the front and rear edges of the dimple SCRUB against the pavement, wearing rubber from the center section of the tire.
Given the factory tire size, you can over inflate more than you can underinflate without experiencing abnormal tire wear although we all know the downsides to overinflation, rough ride and poor tire performance. When you underinflate on pavement, the center wear I try to describe can sometimes happen by being only a few pounds underinflate. Off pavement, the “dimple” causes no wear problem.
The ‘78 4x4 I spoke of, I deflated significantly thinking it would result in uniform wear. I don’t remember the pressures I deflated to, but the underinflation most definitely caused the dramatic center treadwear.
BTW, yes over inflation can ALSO cause center wear. I have never seen a radial tire wear on the outside edges due to underinflation. In fact I don’t ever remember seeing a radial worn on bot outside edges under any conditions. Not saying it can’t happen, but saying I’ve never seen it. In the bias ply days I saw worn outside edges and could safely claim that they were the result of underinflation.
Last edited:
It would be a worthwhile experiment to get a tread depth gauge and keep records of tread depth across the tire width as time goes by.
So many of us have done that over the years on the forum that we have our TJ’s dialed in. It’s pretty standard and no one has come back reporting uneven tread depths that I’m aware of running these pressures.
31’s - 27-28psi
33’s - 26psi
35’s - 24-25psi
WWJBD
The only tires I have seen the low pressure, high pressure wear like you are describing are the wide base super single tires like big trucks run.
Michelin super singles with the way they are manufactured, if they are over pressure they will wear the outside edges and under pressure they will wear the center and that's by design.
McKee bakery did a study and found for their application 105psi was the sweet spot for optimal tire wear and performance. That psi has since been adopted by the industry as the perfect psi.
I have never seen passenger car or light truck tires do that.
I get it! I’m a cheap stuff guy that will wear tires to the wear bars and beyond. The fact that tires have gotten exTREMEly expen$ive of late doesn’t rush my tire purchase any.
That said the lug tires on the Jeep aren’t much good for the purpose when they’re near slick.
Not really, the regular tires, 275/80/22.5 (low pro 22.5 up to the 11R24.5) all will show the same wear patterns as light truck, car and SUV tires.
Only the wide base tires show a different wear pattern.
Similar threads
