i've tried to review the posts to find a solution, but none so far... my 2003 c4s has had vibration problems in the rear since new. P-zero Assym's all around and got a second set of rears and still vibration at 70, bad at 100, horrible at 115+.

had dealer balance and index and had independent balance and index. porsche says ??? they don't know, independent tire store says tires are out of round and they show me on the balancer that the tire is bouncing...

should i keep demanding new tires until the tread on these is even when spinning????

 

I've seen new tires come in already out-of-round, until you can rule out that as a problem you can't go much further. I'd hold out for new tires that meet the proper specs and are not out of round. I had an out of round Pirelli once and it was horrible above 70mph... the ride and the noise...

 

Your tires are probably out round... Pirelli's are notorious for this... see the following thread that has been started recently - go down a few posts...

https://rennlist.com/forums/showthre...threadid=93454

cheers

Peter

 

thanks,

have any of you experienced wheels becoming out of round from bumps, etc. being aluminum, can't imagine it would take much to know one womperjawed.

 

What's the common thread......?

THE WHEEL(S).....!!!!

Brake rotor.....maybe.

 

I've posted before about a similar problem caused by belt shift. It too defied all usual manner of repair and resolved only with 4 new tires. The culprit tires were Pirelli. AS

 

FWIW my Asymmetricos were vibrating at 80+ and balancing fixed it right up. Also, I've found that the tires are VERY sensitve to pressure. The proper C4S specs (36 front, 44 rear) allow them to ride smoother than the lower pressure I was formerly running.

 

get a set of conti sport contact 2's. pirellis suck. their customer service is nonexistent and their quality control is worse!

 

I lemon lawed a car for that. Keep taking it back and get a service recept each time. At some point, they will have to fix it or eat it...

Roy

 

UPDATE

Took C4S to dealer for the 3rd time to resolve rear end vibration at all speeds over 70.

The tech agreed that one tire was bad in that it had a "hop". They replaced that tire. Now the vibration is much lessened and only at 86-90 mph, vs. 70 to 130+. Now I figure I just have the imperfect world of balancing to deal with.

Techs tell me that you can't balance a tire for 100 mph when the balancing machine doesn't get over something like 55 mph. How do professional race teams keep their tires likely more perfect? Surely at their stiff suspensions, higher temps, etc. etc. an out of balance tire would be unacceptable.

 

hahah conti sports, and you say assimetricos are junk? those tires have less grip and weigh more than all. Concerning the assimetricos if you drive them hard - heat them up a lot and beat on them through corners they will distort. However if you drive say in a straight line and let them cool down for about 1 mile or so they go back to normal-

 

the machines today are pretty accurate and sensitive so if you balance a tire for 55 mph it should be balanced for any speed.

i also think that the tires you've been getting are out of round and/or not balanced correctly. any decent tire shop should be able to fix it the first time. i had this happen to me, but i called the manager of the shop, and had it fixed the next day. this was in a toyo tire. which, by the way, are excellent all around tires, though not as grippy as i would like, but that's the trade-off you get when you get more mileage out of them.

 

some tire shops that shave tires, can 'true' tires that are hopelessly out of round, where balancing cant mask the real problem. Yes, having them trued, will take material off, but a round trued tire, should outlast a wobbler, IMHO...

 

sean

with respect, i replaced my p zero assyms with conti 2's. they are much better tires for a daily driver. much better wet traction and much more quiet.

p zero's may be better on a dry track but not for daily use. worst of all pirelli customer service is awful. they would not even replace a tire that developed a bleb on the sidewall at 3k mi even though the wheel showed no evidence of damage. my local tire dealer informed me that pirelli is always hard to deal with. they took 10 days to return my call and a week to respond to their authorized dealer. it will be a cold day in hell when i purchase another pirelli!

 

I'll confirm the report on the Conti's. Mine now have 12,000 street miles on my ttX50, remain quiet, offer good grip, and don't look worn out at all ( I'm guessing about 40% left). The original Pirelli's were far inferior and were junk after 5 hard laps. I did do a full cool down lap (1.8 miles) which clearly did not prevent the problem. The Pirelli's best attribute was surprinsingly good grip in.... SNOW. AS