why are my steer tires cupping?

Heavyd,
What's the proper way to mount a tire then? After improper tread patterns emerge will the tire eventually right itself? IE...good tread catch up with the bad?

 

on my truck I had a big issue with the left steer cupping really bad, took a set of shocks and a new set of king pins and I replaced my tie rod ends.

If your truck is pulling you do have an alignment issue.

 

Basically after the tire is mounted you need to jack up the wheel and spin it to see if the tire is running true. If it is mis mounted you will see it wobble up and down or side to side!

 

I drive a 2007 Volvo and within the past year I'm averaging 24k on steers then replaced due to cupping. Left steer is the first to start then right not as bad. Front end aligned, shocks replaced, fifth wheel greased and still having problem. Truck had stablizer bar attached to steering and I keep my pressure at 100 psi on all tires. This thing has me baffled. Never had this problem on Freight Shakers or Corn Binders only on this Volvo that has air ride on steer.

 

Cupping is when a tire isn't making constant solid contact with the ground. What is the pattern? If it's randomly all over the tire it is normally the shocks. All it takes is one good pot hole to ruin one especially if they are cheapo's. Fatigued springs are another culprit. Cupping on one or two spots can be a balance problem. I would do like heavyd said above and jack the tire barely off the ground and check if she is running true or not. Then see if there is any up/down play and then side to side play or both. It'll tell a story.

Alignment guys sometimes get lazy and won't do a good job. But that would be more of a solid wear pattern.

The quality of the tire can make a difference. But 24K is way too early. Do the jacking up thing and I bet you find something.

 

The center is the steer tire remains untouched from the cupping with normal tread but the inside/outside edges of the tires are effected flattening in areas while other sections of the inner/outer edges cup thus causing vibration in the steering. I questioned the possibility of possible worn shocks as for other worn parts yet my company's answer to the problem is putting more tires on the truck allowing the problem to continue. I'm concerned the problem is a safety issue and my front end will fall out from under me. A mechanic tried to violently shake the tire(s) to check for possible bearing problems but the tire(s) never moved so he stated there wasn't a bearing problem, just replaced the tires. BTW: the tires aren't balanced with weights or any other device. Thanks for your response.

 

My first thought would be shocks. Wearing on the outsides I would increase the air pressure to 110. That's what I normally run on the steers and 95-100 on the drives. Now that fuel is up I've seen some running even higher. Steers run close to max weight so you want to be close to max pressure.

 

The shocks, if after a trip they are not very warm they are junk. they are just a hydraulic damper and convert the energy of motion into heat.
You want to check the bearings and steering components for wear a worn tie rod end can cause a problem. Also a trailer that is dog tracking will also that all you have to do is when on a straight section of road, and no traffic drive with you drive tires on the line, the trailer also should be.

 

They say you can't teach an old dog new tricks. Ruff Ruff... Never figured one could touch the shock testing it for heat indicating it to be worn out. I knew that a driver could touch the center face plate on the drive for bearing problems. I had a trailer with bad bearings like that.

 

Bumping this up.

Today when I was doing my pretrip I noticed right steer tire right edge had a lot of cupping. Took it to a shop where they checked the tie rod ends for play. There was none. They replaced the tire with a USED because they said take it for a run and come back. I drove about 150kilometres and noticed cupping again in the middle of the tire. Also, the truck is bubbling and kind of pulling to the right.

What should I check? Seems like mechanic isnt that competent.