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need some advice with tires cupping
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=45783		 Page 1 of 1
Author:  mngoat01 [ Wed Aug 12, 2009 11:18 am ]
Post subject:  need some advice with tires cupping
I put some yokahama tires on about 5000 miles ago also had the jeep aligned at this time. Was done at a Tires Plus location. Really love the tires but about 2-3 weeks ago started to notice some front end howl/growl noises. Was thinking either tire noise or wheel bearing. Figured i'd have the tires looked at first. Took it back to Tires Plus. They check things over and found the front tires to be cupping. They said everything else in the front end looked good. They made some minor alignment changes to adjust for the cupping and rotated the tires. They also mentioned my large hitch that i have and that i must do some heavy towing. I told them the hitch was stock and that i have not done any towing since the tires had been put on. The only thing I do pull is a single place snowmobile trailer in the winter. I'm assuming they were thinking I was loading the back to much, lifting the front end and causing some tire hop? Any how do you think i should just leave it as is for now or was the jeep just not aligned right to begin with? has there been some tire life taken off the tires because of the cupping or is it just a noise issue i need to deal with? Should i make more of a fuss with Tires Plus? Thanks for any input.
Author:  TAHOE [ Wed Aug 12, 2009 11:32 am ]
Post subject: 
how many miles on your KJ? is it the stock front suspension? Could be the front struts are worn out. You may not notice it driving, but the struts maynot be keeping front tires plantet to the ground causing them to bounce ever so slightly, eventually causing the cupping. The cupping may have slightly shortened tire life, only to the fact it has worn more tread off in certain places. rotation should help in wear, but I would look into new struts possbily.
Maybe someone else will chime in with more thoughts, I'm no expert.
Author:  mngoat01 [ Wed Aug 12, 2009 11:56 am ]
Post subject: 
Jeep is coming up on 50,000 miles. Completely stock(original front end). They did check out the front end but perhaps they can't tell how the struts are doing just by looking. thanks
Author:  DOC4444 [ Wed Aug 12, 2009 12:01 pm ]
Post subject: 
Need more info. If the cupping is all the way across the entire tread face of the front tires, either the shocks are gone or there is some sort of play in the front end that is interfering with the shocks working properly. If the cupping is on both inside and outside shoulders, but not on the center of the tread, they are underinflated.

If there is cupping on just one shoulder (inside or outside) either the camber is off or the toe is WAY off (less likely). Some underinflation of the tires could be combined with a camber problem. (Usually if the pressures are good, you will get shoulder wear that is smooth when just the camber is off.)

I use a racing style tire pyrometer to optimise pressures with different tires and loads. After 30 min of highway running at speed, check shoulder and center temps. When they are all the same, you will get even tire wear. (We run 38 psi cold with stock size [16 in] Dunlop Radial Rover AT SLs in the summer, then go up a couple pounds in winter to get even temps/wear.)

I have found over many years that with many vehicles that even with same size/same load range on same vehicle that optimal pressures can vary by as much as 10 pounds when you switch frm one tire company to another.

DOC
Author:  Joe Romas [ Wed Aug 12, 2009 1:17 pm ]
Post subject: 
i had a factory set of good years on a 99.5 jetta I used to own and they cupped badly for any ownwer that had them on that model and year. They would replace them under warranty but with the same tire. The final word was they were good tires but just not on that car :shock: that sounded like a cop out to me but the second set were Michlins :lol: So it could be just the combination of those tires on a crd. My OEM good years on the crd are still good at 27,000 mile but I do a 5 wheel rotation every oil change per the owners manual.
Author:  mngoat01 [ Wed Aug 12, 2009 1:37 pm ]
Post subject: 
Thanks guys, i'll check into getting more specific on how the tires are cupping. I'll double check with tires plus to make sure i have all my bases covered.
Author:  onthehunt [ Wed Aug 12, 2009 3:07 pm ]
Post subject: 
Some tires are also prone to cupping. Lots of variables to check. Did your last set cup?
Author:  tan's2002kjlimited [ Wed Aug 12, 2009 7:47 pm ]
Post subject: 
TAHOE wrote:
how many miles on your KJ? is it the stock front suspension? Could be the front struts are worn out. You may not notice it driving, but the struts maynot be keeping front tires plantet to the ground causing them to bounce ever so slightly, eventually causing the cupping. The cupping may have slightly shortened tire life, only to the fact it has worn more tread off in certain places. rotation should help in wear, but I would look into new struts possbily.
Maybe someone else will chime in with more thoughts, I'm no expert.


x2
Back in the day when I wrenched, the shocks and struts aren't
keeping the tires on the ground. 50k? Time to lift.
Author:  warp2diesel [ Wed Aug 12, 2009 9:29 pm ]
Post subject:  Check your Tire Pressure
I started having signs of cupping and excess wear on the outside of the front tires.
I checked my newly replaced under recall ball joints and they were good as were the tie rod ends. It will get Moog regreesable when they are replaced.
I increased my tire pressure to 40 PSI and the problem went away, signs of cupping disappeared as the tires wore down normally, and my fuel mileage increased.
I have +43K and I still have about 1/16" left before the wear bars start to show on the original stock Goodyear tires.
I plan to go with Cooper from my local Blaine's Farm & Fleet before the snow flies this fall.

When my Wife's TDI had tire cupping on the rear axle, alignment was with in specs but not perfect, I aligned the rear axle dead nuts with shims, increased the tire pressure and the problem went away.
After I dead nuts aligned the old Jetta's wheels and increased the tire pressure, the tire cupping problem went away for good.
Author:  DOC4444 [ Wed Aug 12, 2009 10:32 pm ]
Post subject: 
Joe made a good point about front wheel drive VWs. I have had many, all with very good shocks (mostly Bilsteins). If you leave the rear tires on the twist axle for more than 5000 miles, they cup across the whole tread to the point that moving them to the front will no longer "save" them. This seems to be a characteristic of the twist axle design and relatively low weight on that end of the vehicle.

In 40K with our CRD we have seen no tendency towards cupping with this platform.

DOC
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