[m-wilhelm]

Looking to get new tires, currently 225x40x18 and 265x35x18 Kumhos. My 968 isn't used a lot, sits in the garage with some track days. I see the Sumitomo HTR Z III get great reviews and the other tire I'm considering is Nitto NT05. I don't care about wet performance or how quiet the tire is.



I have 2 problems with the Kumhos that I want to avoid with a new tire, my Kumhos flat spot really bad and they get out of balance often. In the cold weather the flat spot is really bad, takes awhile for them to warm up and the flat spot to go away. Its bad enough that I rarely drive the car when cold. I've also had the tires balance go out a month after getting balanced, I've heard from several shops that Kumhos are known for this.



Any feedback on balance and flat spots for either Sumitomo HTR Z III or the Nitto NT05s?



Thanks

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[94SilverCab]

http://www.griotsgarage.com/product/in%2...4AodlzI_Xg



How's this?...kinda pricey I thought...



Jay

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[m-wilhelm]

I've seen those before, nice idea but too expensive. I had Michelins before the Kumhos and they didn't flat spot near as bad.

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[flash]

just to be sure that it wasn't something obvious, how old were the tires? don't just go by how long you have had them either - you need to check the DOT number, as they may have been on the shelf for a while - 6 years is the max life of a tire - after that they start doing weird things

how long does this car sit that it flat spots? i've never had radial tires flat spot without a skidding problem creating it



if you have tires going out of balance quickly, i would suggest that you have your alignment checked - it sounds to me like you have an uneven wear issue that is causing the problem - it takes very little toe to create uneven wear that would cause that

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[Jamie '92 968]

Just as a data point...



My last set of tires were Kumho high performance all seasons.

They had a big issue with flat spots, especially in the cold weather, until they warmed up.

Like the wheels were slightly unbalanced for about 5 miles.



I switched to Sumitomo HTRZ III's a few months ago and have had no such issues.



Jamie

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[Scott Collins]

m-wilhelm,



I got the Sumitomo HTR Z III's this summer and I concur with Jamie - no problems with flat spots. OMHO they are a "excellent" everyday tire, and made even better by the low price as compared to other tires out there. Good luck.



Scott

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[m-wilhelm]

My 968 can sit for 2-3 weeks without moving, in the colder weather it only takes a couple of days to flat spot. I'm not concerned with fixing the existing problem but was looking for any info on other tires and flat spots. I've had several good garages tell me Kumhos are bad at holding a balance and I'm a little scared going with another lower level tire brand. I get the alignment checked every year and only put about 2000 miles a year.



Seems like Jamie had similar issues with Kumhos and that the Sumitomos don't have the same problem. This is exactly what I was hoping to hear, thanks.



Anyone hear any feedback on the Nitto NT05s?

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[rxter]

I've noticed the "out of the garage" imbalance as well. For me its a about 1 to 2 miles - I am starting with ambient temps in the 50s lowest. I thought it was the suspension but then noticed it in 2 968s with very different suspensions, but the same amount of sitting in my garage. I have never noticed this with any daily driver that I've had for 30-years - and most of those sat outside and many of them in the snow. Only with these 2 968s that sat in a garage for a week or more at a time. Not sure I'd call this a flat spot exactly, but it does seem reasonable that the tires might be a little mushy and a bit out of balance after they have sat for a while.



Anyone else notice this characteristic?

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[wiseman]

At that price point..buy the ZIII's and enjoy the ride. You won't be dissapointed.

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[nissanite]

Here is a little tire knowledge. Many H-speed rated tires have nylon belt edge strips at the edges of the steel belts. Nylon contracts when hot & expands when cool. The strips help keep every thing together at high speeds. V-speed rated & higher have full cap plies instead of just strips. This addition of nylon is what causes the "flat spots" with cold tires. If the vibration goes away after a few miles, no problem.

Vehicle manufacturers are now stating a car should be started and driven at time intervals. Some as short as 30 days. This became apparent after the economy slid & more cars sat in ports & on lots. Many tires needed replaced because the flat spots would not drive out.

I am partial to Bridgestone products & the Potenza RE-760 Sport tire is a fantastic value top tier product. I have Bridgestone RE-11's on both of my 968s. Best tire I know of but are focused on track & sport street use.

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