sagewolf

This spring tires started cupping getting some vib from some thing, rotated all year, to replace for winter.

Started replacing parts at 75000 miles. Replaced rear u joint, then had front axial driver side u joint done. Then got all new tires mounted balanced put back on same tire from BFGoodrich Rugged trail T/A 265 / 70R17.Tires at 65-70 psi. Was little better. Put on all new force reflex shocks, they raised ride height, old ones were shot. Got all for ball joints, MOOGS put on. Had all four rotors turned backs were warped most. Was better but steering was still a little loose, very small pull. Still have vibration. Now replaced rest of rear u joins, were rusting bad. Had oils changed front, rear, dif. transfer case, and transmission with a new filter. Got one set on tie rods ends on. Would drive on concrete and truck would vibrate very bad at 70 mph (looks like jeep in Jurassic park, watch water in cup holder.) Hole truck would shake and rattle your teeth, no problem steering was easy to hold in lane. As my teeth raddled. Got other tie rod ends on and aligned again. Raised tire pressure to 80 psi in front, 70 rear, no load. All so put on steering shock. So now tires cupping again is noticeably in last 300 miles, slow speeds feels like you are driving over small things. Cupping more on out side of front tires more on driver side. Need help. Am now at 78500 miles on the truck.

CoastalDav

Sounds like you covered it all in structure.

Could be Rims out of round, tires not balanced correctly, broken belts in the tires, to much air in conjuction with another problem in the tire.

I'd say get them spun on a balance machine as is and see what its saying. Make sure they get them centered on the spindle. (watch the tire spinning. don't allow any in and out, left to right movement, or up and down movement)

If they say its out of balance, denote the weights shown on the machine, remove your balance weights (denote the weight removed) and spin it again. If it shows more weight needed than before it could be right. If it shows less weight required than you removed, it could have been overweighted or the previous weights placed in the wrong places. If that makes sence.

Dave

billie

Cupping on the front or rear? I assume the front.

Inside or outside edge?

Toe adjustment is usually the culprit in my experience. Check the alignment at another shop. Did you use the same shop each time? Could be their equipment or the operator.

Cya

Grit Dog

With new bj's and tie rods that should eliminate any cupping from slop in the wheel.
Vibration should only be 1 of 2 things, likely tires out of balance (rugged trails should balance easy and be ultra smooth riding though. Only happen at certain speeds...tires. Low speed vibration: Unit bearings going out?

If you have 80/70 psi in an empty truck, and new shocks it's going to bounce around and feel every little thing in the road much more than the correct unloaded pressure of about 60/50psi.

Tires cupping on the outside (again, Rugged Trails should hold up very well to this), either from alot of high speed curves, or alignment toe problem. Unless somehow the new ball joints aren't right or are adjustable camber, camber could be off

jonny mopar

I have been changing tires now for the past 6-7 years now at a tire shop that does around 60 to 70 tires on a normal day. we do lawn mower to atv's, motorcycles and cars and all the way to big rigs we even also do big farm tractors. but I don't see many of our trucks that have chopping issues like the gm trucks do. Most of the time when we get in a car or truck that has choped up tires it is because lack of rotation, or struts bad on the rear of a FWD. But if you have kept up on rotating them that shouldn't be the case. but How ofter did you rotate them?
Another thing is a RWD "or 4x4" i don't wanna say won't chop the rears but hardly ever chops the rears. it is the front that chops. and vise versa on a FWD.
what kind of shape are your front springs in? And i know you said you had new shocks put on it. But i put a new set on mine when i lifted it and 4 months later they were BLOWN out. oil leaked out of all four past the seals. only thing i do with mine is haul cars and drive it. i don't off road it really. maybe check them out again.

As far as balanceing, no tire runs true. thats part of why they need to be balanced. they are going to have a little up and down side to side runout. and the stock bfg's run extremely smooth while balanceing them. and they useally call for little weight. Maybe you have a bent rim or 2? i had steal rims on my truck when i got it and it had a bent rim. made the tire ware funny and it had a bad shake. 1 more thing about balanceing tires, on a small tiny car you noticed tires out of balance WAY more then on big heavy trucks like ours. you won't notice tires that a 1/4 or 1/2 oz off or maybe even 3/4 oz off on our trucks. and on the back you might not feel tires way out of wack. to put it this way. we don't even balance rear dualy tires unless the customer asks us to do it. and we NEVER have them come back and complain. I have driven my truck without the tires balanced a few times and have barley noticed anything. and that was with 35" mud tires.

As far as a shifted belt goes, you feel them at slow speeds. and it gives you a rocking motion. if the belt is shifted real bad it might shake at higher speeds but by that time you can look at the tire and you will see a huge bauldge in the tread.

air psi. if you are empty try 60 to 65 psi in them all around.it gives you a smoother rde also. if you are heavy adjust them to your weight.

The stock BFG's ware like IRON!!! the traction for any bit of off road suck but they get AWSOME mileage. i have taken them off trucks with 80+k on them and they were smooth as new.

OH and once a tire starts to chop "cup" it is really hard to smooth them out again. depending on how bad of corse. maybe a good ole burnout is needed to smooth them out???