I got into an argument with my dad the other day about what air pressures I should be running on my tires.

In the front I have 245/35/20's on an 8.5 wheel
And in the back I have 275/30/20's on a 10 inch wheel

In his defense, I'm experiencing wear on the insides of the rear tires.
Pretty abnormal wear actually. The outsides of these tires are NEW and the insides are not bald but not far from it.
I would think that this would be from under inflated tires?
Maybe a more serious problem? Should I get an alignment?

I'm currently running 38 psi in the front and 36 psi in the rear.
Is this correct/normal for these types of tire sizes? These are cold temps btw as well.

 

I'm guessing you dropped the car and didn't realign? If you did realign, I'm guessing you've got a good amount of toe. Search alignment specs - thats where your issue is.

Toe + Camber is what kills the inside of your tires.

 

Sounds like an alignment issue

I have similar sized tires and run 36 psi.
Anything in the 32 - 38 range is fine

 

I havn't dropped actually.
Still stock height.

 

Just what I wanted to hear.
Thanks Jedi.

 

i think it could be your driving habit and i think you might have too much tire pressure!

 

Too much air will wear out the middle of the tire tread. Underinflating will wear out both (not just the inner) of the outer edges of tread. While too much negative camber will wear the inside of the tire, it takes quite a bit, say more than -2 to really cause a problem. Toe, rather, too much toe in or out, is the killer for tire wear. I would look at toe first, my guess is since you're still on OEM springs camber isn't the problem.

Another issue is why you felt the need to have huge tires in the rear for a car that comes with understeer and requires some work to get rid of it. I'm assuming its for looks, but that's another issue.

 

Incorrect tire pressures couldn't cause the inside of your tire to wear. Overinflated tires cause the inside of the tread to wear while underinflated tires cause the outside of the tread to wear, not just one side. So your tire wear issue is most likely caused by an incorrect alignment. Like said, camber and toe have a big effect on tire wear.

 

Get an alignment. 4 wheel that is. And have them reset the rear wheel toe in/out. I run 36 psi in my 265/35-18's on 8.5" rims.

 

My car came with these wheels already on it.
I wouldn't have went with someone SO big and staggered had I bought them.
They do look sweet though and I get a lot of compliments.
That said I wish I had normal 18's on it sometimes.
I'm going to get an alignment asap and we'll see how bad the toe is off or whether that is the problem.
Thanks for the help guys.
Glad I caught this before it got even worse.
275/30/20's are not cheap haha.

 

This makes a lot of sense to me. Thank you for explaining it that way.