Tire Cupping

[sroth004]

All,

I realize this topic has been covered in the past, introducing it again hoping for new insights. Newish tires on my ‘94 Explorer are cupping badly with roughly 10,000 miles on them that the truck is almost undrivable between 64 and 76 miles an hour, with shaking noticeable at lower speeds, less so above 76. You can actually feel the variance in tread block height if you run your hand over a couple of the tires, worse on the right side. The X has about 78k miles, the suspension and various driveline components have been checked by two shops and indicated as being fine. I did have the radius arm bushings replaced when the tires were installed with, I believe, Moog parts as the shop which I trust fully felt these were worn and needed to be replaced at that time. Bilstein shocks at all four corners are also new. I’ve had the tires rotated three times since being installed. Tires are General Grabber A/T X LT235/75-15 on stock wheels which I've had checked for round and balance/true as well as having the tires rebalanced a couple of times. I went with the LT-sized Generals as I wanted “three peak” snow rating versus all-season m+s and these had great reviews and pricing. There were no “P” sized tires with the snow rating at the time in the correct size but several do exist today.

As mentioned, I’ve researched and read many of the prior posts on cupping and I am hoping there are new suggestions. any thoughts would be appreciated.

Thanks

Steve

 

[RangerX]

Alignment? Ball joints? Bearings? Do you have a lift, and if so, what is it?

 

[DaSovietPotato]

I feel as if this is most likely a bearing issue which would commonly cup tires, however ball joints could also be a factor.

 

[sroth004]

Thanks Gents, Right side upper ball joint is out by a minuscule amount according to the shop but they didn’t think it is out by enough to fix; I’ll fix it in the next couple of weeks. Thanks again.

 

[mcfixstuff]

Mine are like that too, but I think its because I have old 2017 Rugged Terrain tires. I replaced all suspension components, and have a 1 inch lift. Perfect alignment too. My theory is uneven wear due to spots on the tire being harder than other parts, thus wearing unevenly.

 

[sroth004]

All,

Circling back with the resolution to the issue…right front wheel bearing was slightly loose and one radius arm bushing was installed incorrectly by shop at time of tire purchase resulting in inability to correctly align front end. Different shop that focuses on four wheel/off-road vehicles replaced the radius arm bushings, adjusted bearings, installed steering stabilizer (my request), alignment and replaced tires with Vredestein Pinza AT. Alignment was brought into spec and vibration problem solved. Thanks to all who shared suggestions.

 

[410Fortune]

that stinks!! Incorrectly installed parts cost you set of tires

 

[mcfixstuff]

Too bad nobody trues tires anymore

 

[BKennedy]

There are not many shops out there that can properly align a TTB suspension. They were few and far between in the 90's, and less now. You need to find an old-school alignment shop with an old timer alignment tech.

Glad you got it worked out, but how did they improperly install radius arm bushings? Maybe put one side in backwards?

 

[sroth004]

Sorry for the delay, have not been in the forum for a bit. Not sure if the radius arm bushing was installed incorrectly or if it worked its way out over time, probably a bad install as the original shop indicated at that time that they could not get the (I believe) camber within spec. That shop is “old school” but they have younger techs as well. The shop that ultimately resolved the issue focuses 100% on 4x4s, including old ones, so I figured if they could not solve the issue nobody could. Coming up on 1,200 miles since the repair and new tires and all seems good. I have a slight vibration at about 65 that stops just over 65 so I am good with the outcome.