The front tires on my truck have tire cupping and the steering wheel shakes under certain speeds and road conditions. I know that my brake rotors are warped and will be replaced along with the upper and lower ball joints. I have read that the cause of tire cupping can also be from bad shocks. Is there a way to check and know for a fact if I also need shocks? I hate to have to spend so much money but also do not want to ruin the new tires that I will be getting after I finish the work. Is there any other component that could be causing the tire cupping?

 

Normally it's caused by lack of rotation, out of balance, and alignment.

 

I am a little guilty on that. I will have to get an alignment after I replace the ball joints and the new tires will take care of the balancing.

 

I have the same problem with vibration at about 45mph... brought the car to NTB for an alignment and was told my alignment is good but my tires have cupping as result of worn Air Shocks/Struts... I was told "once the air shocks wear they will not hold the tire to the road and as a result you will get cupping"... ?? not really sure how to replace my air shocks... guessing it may be my damper shocks that need replacing. If I rick the vehicle from side to side it does bounce a bit... Any suggestions.. I have a 2002 II with 78k miles??

 

First, an alignment issue will not cause a vibration, second, you do not have air shocks/struts.
You have convential shocks with either springs or springs in the front and air bags in the rear.
How many miles on your truck, what air pressure are you running, how often do you rotate your tires and have you had the front drive shaft rebuilt or replaced?

 

Mike,

I have 74K miles on my truck with air suspension in the front I assume on all 4 wheels... I think the shocks on the back are technically dampers... anyway air pressure front is 46 and rear is 30... I inflated tires to whatever it said on drivers side door face plate... I did increase the tire pressure when I bought it as it steering felt sluggish...

 

This is scarey, your having issues and you haven't even looked under the truck to see what is going on.
First, you have SLS, air springs only in the rear, try running 40 pounds all the way around.
Your biggest cause for tire cupping can be, wrong air pressure, lack of rotations, warn out shocks and steering damper.
So, how mechanical are you, or do you use a shop, and at your mileage have you had a complete major service including the rebuild or replacement of your front drive shaft?
Might want to read my major service list at the top of this section.
Also with tire being cupped, they will wear out much faster and won't balance well.

 

I do most of my own car work... tune ups, breaks and recently completed a head gasket replacement on a 1997 Dicso. Not familiar with SLS but have definitely replaced my share of shocks/struts... I will try changing the air pressure as well a the steering and rear shocks... I just bought this disco last week so not familiar with what work has been done on it... The other thing that I was considering is that this truck may have been sitting in the lot for awhile and have flat spots?? so maybe this problem with self correct. I will keep you posted.

Thanks for your suggestions Disco Mike... much appreciated

 

Todays tires are not made of nylon as in the past and do not generate flat spots/cupping.
Might want to consider a replacement set of Old Man Emu shocks from British Parts of Utah.