Tire cupping

[87Skier]

I've got an 89 Suburban 3/4 ton 14 bolt rear, corporate dana44 front, and my front left tire is cupping on the outer edge. It has 230k miles. No lift and it is running the stock 235/85r16 tires.

I bought the truck last year, it had been passed around a few times, so no previous information on it. Had three new tires when I got it, with a 4th relatively new, but different style. All four tires are the same size.

Truck clunks from front end occasionally. I thought it was the sway bar so I replaced the bushings on the frame and didn't have any luck. I did the brakes on it last year, repacked and checked all bearings. Everything rotates smoothly, but I do get a slight vibration at highway speed. Not sure if is the bearing or the tire. Truck has very tight steering, no slack or wandering.

Any ideas of things to check or look at?

Thanks

[mongocanfly]

Sounds like ya need to visit a alignment shop for the tire issue,, hard to say what the clunking is..does it have fulltime 4wd or manual hubs..I had a 86 once that would shake if you left the hubs locked in at higher speeds even though the transfer case was in 2wd..unlocked front hubs and my problem would go away.could be that bad tire causing your slight vibration.

[tucsonjwt]

I have always heard that tire cupping was due to bad shocks.

Is the cupped tire the odd one? A cheap tire could also cup.

[87Skier]

Originally Posted by mongocanfly

Sounds like ya need to visit a alignment shop for the tire issue,, hard to say what the clunking is..does it have fulltime 4wd or manual hubs..I had a 86 once that would shake if you left the hubs locked in at higher speeds even though the transfer case was in 2wd..unlocked front hubs and my problem would go away.could be that bad tire causing your slight vibration.

It could be that the hubs are stuck engaged (it has auto hubs). I might take it out on the highway to compare the difference when I have 4wd engaged and not. Transfer case is a 208 so part-time 4wd.

The tire that is cupping is on the same axle as the odd one. Eventually, I will rotate the tires and see if they cup again, but not yet. It could probably benefit from some new shocks. It has dual shocks up front.

I'll probably do some investigating soon and check for any worn items, and do a quick driveway alignment check. Check toe, camber and overall square.