A mysterious tire leak.

[ikessel@worldnet.att.net]

Hello, folks.

I have officially given up on this issue. Perhaps somebody can shed some
light as to where the hell does the air go?

Right before X-mas I decided to remount the summer rubber on my both
quattros and found one of my Hakkas to be at 15psi after summer storage.
The remaining 7 were at 24psi uniformly.

OK, a slow leak. Mounted the tires, overinflated them for the cold
weather to 37psi in my garage at +15œ, figuring that at -5œ outside they
would be about normal.

A fortnight of driving revealed that this one tire lost pressure at a
steady rate of ~ 3psi/week.
Took the wheel off and scrutinised it. No foreign objects whatsoever.
The alloy rim is straight, has never been hit. The bead sits evenly.

Sank the wheel in the tub in one of the bathrooms (don't tell my wife).
Not a single bubble came out! 
I went through the wheel with a fine comb, tilted it under water at 45œ,
first one surface, then another, to catch any possible leaks from the
bead sealing area. Nothing.
Took the valve cap off. Checked the valve. Nothing.
Depressed the little dimple on the valve. A train of bubbles came out.
Released it and it sealed perfectly well again.
Wiggled the valve stem violently in its nest. Nothing.

C'mon, it's only a tire! Only a hair more complex than a coat hanger. I
have found and vulcanised or sealed hundreds of tire punctures in my
life yet I don't seem to find this one.

WTF?

--
Igor Kessel
Two turbo quattros











a4