HDClown

I have 4 225/40/18 Kumho 712s mounted to 18" REs. When you look at the tires on the balancing while they rotate, you can see slight "wobble" from the tire. Probably from a high or low spot in the tire itself. It does not appear to be rim related.

The rims/tires return OK on a Hunter GSP9700 balancer and they do 0 balance fine. But this wobble is visible.

I've still having slight problems with vibration at LOW speeds . Highway cruising is pretty darn nice.

How much of a wobble from a 0 balanced tire should be acceptable? I realize the Kumho is a entry level high performance tire, but I was expecting the ride to be smooth, am I asking too much?

ex-quattro PETE

All tires (hell, all products for that matter), have some number of manufacturing defects which slip through quality control (or pass through low quality standards). Some manufacturers have more defects than others, but they all do.

Given what you described, you may have a tough time proving your case though. Is this "wobble" present on all 4 tires? It would be highly unusual for all of them to be defective.

Did you try calling up Kumho USA, if the tires are under warranty?

HDClown

I think I will call Kumho for advice.

HDClown

Tires are warranted as long as they are within 2/32 of original tread depth. I'm at just under or right at 1000miles so mine should be. Basically you take it to a Kumho dealer, they will inspect it and if it appears to be bad they will warranty it.

The Discount Tire I happened to have them re-balanced at is the closest Kumho dealer so I will call them to inquire further.

ex-quattro PETE

try to ask Kumho to reimburse you for the mounting/balancing you'll have to do as well.

Not sure if they'll be willing, but it won't hurt to ask. :-)

HDClown

Im now dealing with local Kumho dealer of Discount Tire who has once GSP9700'd the wheels. They will recheck. I'm going to assume they will all recheck fine. If they do, it doesnt seem like the manager is "pleased" with the idea of possible warranty.

Kumho says the tire has to be 2/32 within original tread to warranty, Im pretty sure it is. (pulling the wheels off today so I dont wear them down anymore infact).

As I said, there appears to be vissible "hop" in the tire while its spinning on the balancer. I'd expect the GSP9700 to account for this. There may also be some visible "hop" at the side wall level and not the flat surface of the tire. I didn't expect personally very much, but the guys at my dealer noticed it on 3 of the 4 tires.

How would you progress with this issue if the GSP9700 returns a proper balance when re-checked? Assume NOTHING wrong with the car (alightment, suspension, etc). All that is left is rim, tire, and driver obsession.

Would you blame the rim? If so, how would you verify to the consumer the rim may be good or bad w/o it costing them.

Would you just go ahead and warranty the tires if you notice the "hop" issues I speak of?

Would you just tell the consumer that sometimes this little amount of vibration is acceptable (altho quick survey of kumho owners reveal no such problems)

Eddie@Tirerack

Well, in a nutshell, for a tire to be "bad" they have to measure outside fo a specific variance (which the 9700 is the best at testing/catching)

The wheel could also be a culprit as well, I suppose.

As an example of what we do, if you suspect there is a problematic tire, we typically sell you a new one to replace, have you sen back, or we pick up, depending, then we inspect it & if found to be a problem you are pro-rated a credit from that tire purchase. Other hand, if not defective, then you have boyught an extra tire.

My customer serivce dept can give you specifics on warranty- call 800.428.8355, ext 360

Hope this helps!

Hartmann/Achtuning

I also spoke with Kumho about my flat spot problem in the mornings. They told me that all tires with nylon outer bands will do this especialy in the cold. I found this answer to be a little BS for this has been hapening all summer long. I think you get what you pay for.

ryoung

.
in warm or cold weather, and essentially all tires with a speed rating of V or better have nylon caps.

In cold weather, it just takes longer for these tires to warm up and smooth out. With my S-03, the vibration is especially noticeable if the car hasn't been driven for 2-3 days.