boca996

Today my passenger rear stock Conti valve stem failed somehow and the tire went flat. I know it is the stem because I used a compressor to partially reinflate the tire, and when I move the stem toward the rear of the car, the air rushes out. I have had many cars and tires in my life and this is the first time this has happened to me. I would especially not expect this to happen on a Porsche approved stock tire <img border="0" alt="[grrrrrrr]" title="" src="graemlins/cussing.gif" /> . Anybody else have this happen or have any idea as to the cause?

I'm having it taken to the dealer tomorrow (should be interesting).

NMoore

The stem is not part of the tire, it's part of the wheel.

ettsn

This is pretty common on high performance cars. I used to cut down valve stems about once every six months on my M3, until I switched out to Motorsport metal valves. There are several issues at work here: heat, centrifugal stress and pressure. The heat from tire friction and brakes will weaken the rubber, while high speeds will cause the stem to stretch outward under centrifugal force. These combined with the generally high tire pressures we run all collude to eat tire stems. What to do? Next time you get new tires, look into getting some metal stems (the full-threaded kind). In the meantime, Porsche makes a tirecap that screws on like any other cap, but has a jacket that comes down to cover most of the stem. Best part is they're cheap and look pretty cool too! (PN 000 044 600 00) The jackets will keep the stems from bowing out under high loads. There's also some stem supports available, but I don't have the PN handy (I'll look for it). HTH

-Paul