[DeTomaso] Rubber based valve stems - Lessons learned and passed on

[Mike Thomas]

Many if not most of you are probably aware, but for those who aren't (which
included me until a week ago), rubber valve stems can be a liability on our
cars at high speed.

I have a set of 17" Campy clones which were put together with rubber-based
metal valve stems.  I had a low tire issue on a club event this last weekend
that almost left me stranded.  I had to limp between gas stations for about
10 miles until I could get to a tire store to have the stem replaced.  The
rubber base of one rear valve stem had started to tear out toward the inside
of the wheel.  After talking to one of our members, it seems that the
centrifugal force put on a rubber-based metal stem at high speed can damage
the seal over time.  The faster the wheel turns, the more the stem wants to
bend to the outside.  With the fancy metal valve stem caps, it's even worse,
as there is more weight at the outer end of the stem.

Solution, as I am told, is to have metal-based valve stems installed.  They
should only need to break the bead on the tire at the stem, and shouldn't
need to rebalance the tire, as the weight difference between rubber and
metal stems is minimal.

Just my .02, hope it helps someone.

Mike Thomas
Panteras Northwest