Tire cupping

[tmavrk]

My 2006 GT has about 36,000 miles on it.
I replaced the original Goodyear tires with BFGoodrich G-Force KDW Ultra High Performance 205/50ZR17 93Y NT [Costco] at 19,000 (1 year ago). Road noise was slightly elevated from original. Tires were faithfully rotated every 5k miles. Now I am getting road noise at 40-50 MPH. Dealership replaced the wheel hubs with no improvement to noise. Costco noticed cupping and suggested alignment. They said another rotation would do nothing about abating the noise. The dealer proved that new tires ($700) would rid the noise. Costco now says shocks/struts need to be checked.

Is it the shocks/struts that are causing tire cupping/noise like this on my GT? I think the dealer should have recommended if they were needed. Anyone with similar problem?

Thanks...
Tom

[NCPTCruiser]

most often, "cupping" is a result of underinflation...have you been lax in checking the tires air pressure?

[tmavrk]

I can only assume that when tires have been rotated/balanced that the correct tire pressure was applied then. Regretfully, I don't check the tire pressure more often. Never have I checked the TP on any other vehicle (other than when flat or obvious low pressure) in my life. The TP is set at 38 on these unidirectional tires. Usually a "cupping" can be resolved by cross-rotating, but that isn't possible.

[Bosch]

I would say at 36K your shocks/struts should be fine.

KDW's are a loud tire when they wear, I have found out from a few friends that got them and now they are getting louder as there life cycle ends. And they are a sticky tire that would get chewed up easy. Also same friends have torn up a set with just one or two trips to the track drag & road course.

Alignment would cause issues, are you lowered? The Toe in needs to be adjusted for the lowering. Do check the alignment at least once a year? I know you probably have now. But gotta ask the dumb questions

And how are your roads? I have learned since moving to Washington state that people run studded snow tires tear up the roads and my PT which was quiet in a relative way is now almost unbearble. Its not the PT its the roads, have been chewed up since I moved up here. It could be a compounding of your issue.

Tire pressure for the PT is a must on the check list. I have found owning two of them that they can be sensitive to it. Just a few PSI low and handling suffers. And with performance tires the tires themselves can be more sensitive to minor changes.

$700 for tires sounds steep? is that the same tire installed? I would shop around or search here and on ptcrew there are many tire threads about good tires and where to find good prices for them.

I hope some of this helps.

[Cal Cruzer]

Originally Posted by tmavrk

My 2006 GT has about 36,000 miles on it.
I replaced the original Goodyear tires with BFGoodrich G-Force KDW Ultra High Performance 205/50ZR17 93Y NT [Costco] at 19,000 (1 year ago). Road noise was slightly elevated from original. Tires were faithfully rotated every 5k miles. Now I am getting road noise at 40-50 MPH. Dealership replaced the wheel hubs with no improvement to noise. Costco noticed cupping and suggested alignment. They said another rotation would do nothing about abating the noise. The dealer proved that new tires ($700) would rid the noise. Costco now says shocks/struts need to be checked.

Is it the shocks/struts that are causing tire cupping/noise like this on my GT? I think the dealer should have recommended if they were needed. Anyone with similar problem?

Thanks...
Tom

Old school thinking is that bad shocks can cause cupping but you would notice the effects of shocks that were that bad (very bouncy, car does not settle after 2 strokes when bounced).

Cupping can also be caused by loose assemblies, bad bearings or even tires out of balance. If your car isn't real bouncy I would say it has to be something else.