GreggT

Guys...I've had this problem of my Sport Cups rotating on my Turbo hollow rims (on the track).....as you might expect, the rear wheel spins forward in the tire and the front is just the opposite (from braking).

The fellas at the Michelin truck thought it was a curious problem and after we got beyond the possible tire-rim size questions, they thought the mounter may have used a lube that kept heating up and slipping.
I don't think that's the case, my shop is Kelly Moss Racing and they have even roughed up the rim for me and then remounted....and I believe either use Sliptac or Rubilite (sp?) for mount lube.

Has anyone had this issue or experience w/any lube product that gets the tire on, but doesn't help it move later?......TIA.

JB '87 944

I believe I'm having the same problem - given my tires keep going out of balance. Can only think they're rotating on the rims. I'm on the original phone dials 17 yrs old. Does the inside of a rim become "slippery" after a while? Would moist air inside the tires accentuate this problem?

GreggT

Easy check of whether it's happening........put a small white dot (or whatever) on the tire right near the rim to correspond w/where your valve stem in the wheel is.
In one 20 minute track session I could have over an inch in movement.

JB '87 944

Thanks... a nifty little trick. I'll do that. At least it will confirm my suspicions. However, if true it won't solve the problem. Hope to see others respond to this thread.

User 462021

I'm not sure if this would work or not, but you could go to a tire shop and have them put some bead sealer between the bead and tire. That may help it from slipping some. The stuff that we have is from Myers Tire Supply and its black, so you have to make sure you don't get it on the outside of the rim. Its a biatch to get off. If you don't know what it is, its like a rubber cement stuff.


HTH

Matt H

Your problem is called tire chatter and it happens on all cars to a certain extent. Dry lube might help a little. The answer is bead lock but I doubt you want that on your Porsche. You might try tire black I seriously doubt it will help. I can try to get you a better answer on Monday.
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GreggT

Any ideas welcome Matt....thanks.

Matt H

Be happy to see what I can come up with as an answer.
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Matt H

Gregg - according to the tech guys they think you have one of two problems.

1) air pressure too low, which could be but is not that likely since this is on the track.

2) someone used petroleum based tire lube when they mounted the tires, as you suspect when this heats up it is nearly impossible to form a tight seal (great for mounting tires on most cars because it is extremely slick). They suggest using a dry mount lube and also warn that tire chatter can ruin a tire as the sidewall is moving at a different velocity than the bead area of the tire.

Interesting problem but they say it happens all the time.
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GreggT

Thanks....pressure is not the issue.

We've decided to make my car a 'lab rat'.
New tires and super clean wheels.......then put Rublite drylube on the left and Sliptac drylube on the right and see which is better (hopefully one is, or both are).

Matt H

Sounds like an interesting test. I suspect both will be fine, it is the liquid petroleum type lubes that arent great for your application, though they are fine for every day tire mounting.
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JB '87 944

Gregg T...thanks for being the test tube baby...look forward to the results.

GreggT

OK.........the results from my test are in.

Back from my 1st 04 track weekend (great time ) and I'd mounted the left Pilot Sport Cups with Sliptack and the right with Ruglide.....both are mount lubes suggested by the Michelin crew.

The Sliptack side did not move .......RuGlyde did.
So Sliptack will be what I specify in the future for my track wheels.

Dave E

Where can I get Sliptac?

GreggT

Sliptac where?.........I think just about any tire supply......Moores & Myers are a couple......they have web sites.