Why are my tires cupping?

[BigMike]

Put a new set of new Les Schwab Wild Country Toyo's tires on my truck a few months ago. I had them rotated recently with about 7000 miles on them. The tire dealer noticed that there was some cupping wear occuring on the fronts. Said it might be an alignment problem, under inflation, too long between rotation. This is my third set of tires on my truck since I bought it and I've never had this problem. I keep my front tires inflated to about 55 psi. Yesterday I had an alignment done and they said it was fine, so I can rule that out. I'll watch the current fronts carefully to see if the problem keeps occuring and will probably have them rotated again at 5000 miles. Any other ideas about what could cause this kind of tire wear?

 

[fkovalski]

In general, cupping of tires is caused by shock absobers not performing correctly. The bouncing effect due to this causes "periodic" contact of the tread to the road. I would check your shocks. -fjk

 

[BigMike]

I thought the same thing fjk, but they dismissed it. What should I look for on my shocks to indicate needing replacement?

 

[Pit Bull]

Originally posted by BigMike

I thought the same thing fjk, but they dismissed it. What should I look for on my shocks to indicate needing replacement?

BigMike if these shocks are the OEM's they were not very good to start with. Put some Bilsteins in the front you will think you have a new truck. I had a 2000 3500QC 4x4 that I put Bilsteins on at around 40K miles, big difference. When I bought my 2002, I changed to Bilsteins within the first 3K miles. Try them you will like them. I still run the OEM's on the rear since I don't tow or haul that much and they are just fine.

 

[fkovalski]

The simplest way (at least on cars) is to do the "bouce test. " Press up and down on a fender corner to get the vehicle bouncing and then let go. It should stop within one cycle. i am not sure (with our truck's springs) if you are able to do this. Are you still running stock shocks? If not, what is the milage of the replacements?

 

[athompson]

I was taught that the cupping was caused by the tire bouncing due to worn shocks. Any "tire man" worth anything knows this. Either this guy doesn't know squat or he was just trying to scam you into work you don't need. All of the "causes" he stated have specific wear patterns you didn't mention. Either way, I'd find another tire shop.



Forget testing the shocks. Just change them.

 

[BigMike]

Still running stock shocks with 74,000 miles. Probably about time I changed them huh?

 

[fkovalski]

I am still running original stock shocks at 40,000 miles with no adverse symptoms. At your milage and the conditions described, I would replace the shocks with a good aftermarket brand. I will not recommend brands as there are quite a few opinions to this and I will let others chime in with suggestions. -fjk

 

[BigMike]

That was my next question fjk. What kind of shocks? I've heard good things about Bilsteins and Rancho's. I don't think I need anything adjustable. Most of my miles are highway and when I'm towing, I use my airbags. I know they aren't a replacement for shocks, but it rides just fine. Rough as hell!! Isn't that normal??



Thanks for your input.

 

[fkovalski]

Uh oh, You might as well have asked "which brand of oil should I use?" Seriously- There are a lot of threads on this topic. I have subscribed to a few and read all new ones posted as I will probably need shocks soon. I would do a search on the topic and prepare some time to a "little" reading! Members reading this thread this eveing will no doubt chime in. Good luck and I will follow this thread too! -frank.

 

[fkovalski]

Here's a couple o' threads: shocks

shocks 2

 

[stacerbob]

Can you post the readings of your trucks alignment here??? You can have your truck checked and the "computer or the factory specs" may say your truck is fine. They give a wide range and if it is in that range then it is good, by the specs.



athompson just wondering how long you have been a "tire man"??

 

[BigMike]

I don't have the readings. I took it to Schwab's. They said it checked out fine and didn't charge me a dime. That's why I like Schwabs. They don't think bad shocks is the problem. Who knows!! They told me to rotate more frequently. Also told me to bring it in after about 1000 miles since rotation and they'll take a look and see if the fronts are still wearing unevenly. They didn't try and convince me I needed to buy shocks. I think it's time to change shocks anyway. They can't last forever! So now the question is: What kind of shocks should I buy??

 

[Rebel_Horseman]

I've noticed a similar thing on my new-to-me truck. 141k on the ticker and it looks like stock shocks to me. I wonder if it's time to replace them? I had Bilstein's on a Z71 and loved the way they rde. Thinking about Rancho too (the colors will match my truck and I've heard real good things from them).



reb [><]

 

[Pit Bull]

From what I have read on this site. Members that have run both Rancho's and Bilsteins like the Bilsteins the most. The advantage of the Rancho's is the adjustable shock is good for towing to customize it to the load. If you tow alot put Bilsteins on the front and the adjustable Rancho's on the rear.

 

[WDaniels]

Stock shocks at 74,000! You pretty much can take it to the bank that your cupping is from the shocks.

WD

 

[athompson]

Just a few references

http://www.autoshop-online.com/cchtml/tire. wr. prob.html



http://www.shorelander.com/pages/o_tirewear.html



http://www.metropark.com/safewaytire/tireware.html



http://kaltire.com/commercial/medium_truck_tires/cupping.php



http://www.tampaautocare.com/tire.pdf



http://rollingmotors.com/tires.html



http://www.infodotinc.com/basae/234.htm

 

[Hammer]

There are numerous things that will lead to the conditions you are having. Since you have checked the alignment then we can rule it out,but,when they did it, did they do the complete deal(toe in ,toe out,camber,caster)?. If so it can be one or a combination of all these combined.



-Trac bar worn.

-Static balanced tires(meaning all weights on the inside of bead).

-Shocks worn out.

-Bent factory wheels(the steel directionals were known for this).

-Underinflation(yes I realize that DC say the pressure that you have in is ok,BUT,it doesn't mean the tires will).

-Ball Joint problems

-Sitting still and turning the wheel hard one way or the other without rolling the truck some.

-Worn out Steering stabilizer.



Many of the above will contribute to this problem. The one I feel is the biggest problem is pressures. We all know DC says to run them softer to facilitate a softer ride,BUT,it will shorten the life of any tire by doing that. Most of todays tires are engineered for ride or traction in severe or extreme conditons which means a softer compound. This coupled with lower pressures and the weight of the front of our trucks causes the cupping. It is best to run a softer compund tire closer to its actual recomended pressures for longevity. By rotating them sooner you will keep the cupping in check if you desire the softer pressures.



Hope this helps some... ..... Andy

 

[stacerbob]

Put on the bilsteins. Don't rule the alignment out yet. It can be "in alignment" by factory specs and still cause the same problems you are having.

I would echo to have someone look at your tires in 1000-1500 miles to see what they look like. If you can have them check it again and get the readings post them here or send me a pm.

 

[fkovalski]

Big Mike-

Following up on what Hammer said: Check all the alignment specs, but on a 4WD the only feature that can be normally be adjusted is the toe. Caster is pretty much set and usually the only way that camber can be adjusted (on a 4WD) is with eccentric ball joint bushings. I am not sure if our trucks have these. BTW- what size tires are you running? I ask this because I run my truck stock and this is my experience with it: I ran the stock Mich's till about 35K miles and then noticed tire wear on the right front only. No cupping and I did not rotate the tires at all. The right front was wearing on the outside without feathering; thus indicating to me that toe was not a problem. It was pulling slightly to the right. I took it to the dealer before the warranty was out and they replaced the ball joints and track bar (no big surprise. ) I did an alignment and replaced all 4 with new tires. Now it tracks fine.

Sorry to be long winded, but what I am getting at is:

Wear on sides of tire w/o feathering (inside or out)= camber (ball joint issue)

Feathered wear on sides (inside or out)= toe issue

Cupping= periodic contact of tires with road= (shocks)

These are generalities and there could be a combination of factors. From what you described, I would definitely replace the shocks.

Apologies to all who read for my soap box. Keep us posted -fjk