put new tires on about 6 months ago (grabber2) the tires they replaced(bridgestone dueler) had really bad cupping on both tires inside treads. my u joints were bad at the time so i blamed them. its been a couple months now since the u joints and the new tires are starting to cup inside on both. Also I think one or both front hubs are bad but ive only been hearing that sound for a couple weeks.
Any clue why my tires might be cupping??

 

Bad shocks, front end alignment-camber, bad hub/unit bearings. too much negative back spacing on wheels. JMO

 

I'd say tire balance, or an alignment issue.

 

X2

In addition, the only alignment setting that is adjustable on 4WD is the toe-in.

 

That's incorrect. On the ZJ the front LCA's to axle attachment points are cam bolts for adjusting caster. I would assume the XJ would have the same set-up.

 

I have had both my XJs, an '87 and a "92 aligned recently (the '87 yesterday) and in both cases only the toe-in could be set. Thats all I was charged for.

On the '92, the mechanics discussed with one another that on 4WD Cherokees (XJ) with the solid axle only toe-in could be set.

I am not familiar with ZJ arrangement. I would not assume XJ front end is the same as ZJ without definitive proof.

 

You're correct, they're different. On the XJ the camber adjustment is done at the rear of the LCA's.

 

Thats good to know that it can be done.

 

It's in the manual but most people and shops ignore it.

 

yeah it took the guy that did my first alignment like and hour to figure it out but now that i have adjustable arms it is a lot easier