Rear Tires Cupping?

Thrust is .25°.
Good or bad?

 

That’s fine.

General rule of thumb allows .50*

 

I have had E rated 285s and E rated 315s. I’ve never gone over 35psi. In fact my 315s are at about 25-28psi right now and are wearing evenly using the chalk/water test


Not saying you’re doing anything wrong but that’s a lot of psi.

I could be totally wrong and be about to learn something..

I forgot to ask; what size tires are you running?

 

Are your fox shocks compression or rebound adjustable?

 

285/75r16
Do you have any extra weight on the rear?
I’m not saying the mechanic is correct. Hell, I NEVER use a mechanic so this is tough for me to follow someone else’s advice on my rig.
He said it appears to him that the tires are wearing on the outside edges, both in and out, which is under inflated. I don’t see what he sees on the tires so I’ll just play it by ear.

 

No.

 

You can get a shop quality tread depth gauge on Amazon for $8, if you’d be interested.

 

Didnt see it listed, but what tires are they?

 

Low psi sometimes exaggerated by too narrow of a rim will generally cause rear cupping. Wider tires need wider rims. Just dropping pressure or running at lower pressure to get "chalk test" results doesn't always work well. 285 mud tires need to be on an 8" or wider rim to get maximum wear characteristics.

I'm currently at 44K on a set of STT PRO's that ride and wear as smooth as a babies butt....9" rim and 38PSI. I'll EASILY get another 25K before hitting wear marks.

Rotate often. especially until you get tires worn flat again. 4K to 5K MAX. Left front to left rear. Left rear to right front. Right front to right rear. Right rear to left front. If tires are cupped, it will take 500 to 1000 miles after rotation to wear them back to "flat". No such thing as immediate gratification when correcting improper wear.

 

I have one here at work. I’ll check it. Thanks for the idea!

 

Maybe 50-100lbs of tools and crap almost always. Yeah I know what you mean about following others advice lol.