Chuck--

No offense, but you need to buff up on your tire IQ. The reason racers
switch out tires in IMSA/NASCAR etc. is because the tread compound used
for racing tires is purposefully super soft to provide excellent
traction at very high speeds. Soft compound wears out fast, but can keep
3,000 on the road when cornering at 65 mph.

Certain racing tires have harder compounds, and racers select these for
hotter race days, since they *can* last longer but not by much. If it is
cold out, the 'gummies' come out. They are literally sticky to the touch
at room temp. Tire selection is part of the competition at IMSA races...
which to choose???

Tire design is a series of complicated trade-offs:
Long-wear v. harsher ride
Long-wear v. worse traction
High-speed capable (structural integrity) v. decreased comfort
High-speed traction v. long-wear
Noise v. wet weather traction
Long-wear v. cold weather traction
Noise v. mud & snow traction
Price v. any of the above
Etc. etc. etc.

You act like we've never sent a man to the moon. Of course the
technology exists to create tires capable of sustained use at 200 mph,
that can last for 40k miles, but the lack of market need, and the
(aforementioned) trade-offs make them un-saleable, so they aren't
produced. Racers couldn't use them because they couldn't handle a corner
at 70 mph, they'd have to slow to 15. Citizen drivers would find them
astronomically expensive, and harsh to ride on. Etc.

Grew up with a tire design engineer as an 'uncle' (filmy friend, no
blood).

Bringing your ideas to life,
G. Matthew Bulley
Bulley-Hewlett
Business: www.bulley-hewlett.com
AIM = IExplain4u
Phone: +1.919.658.1278

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf
Of Chuck Mathis
Sent: Monday, October 07, 2002 3:32 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: High-speed Tires, (was Porsches' stupid uninventive vehicle
(SUV))

But those tires are never used for more than one race.  Frequently pit
crews change tires several times during a 500 mile race.

Chuck

In a message dated Mon, 7 Oct 2002 12:06:26 PM Eastern Standard Time,
LISTSERV@GERRY.VANAGON.COM writes:

> Date:    Mon, 7 Oct 2002 10:40:02 -0400
> From:    "G.M.Bulley" <gmbulley@BULLEY-HEWLETT.COM>
> Subject: High-speed Tires, (was Porsches' stupid uninventive vehicle
(SUV))
>
> "However no tire will handle 168mph sppeeds (sic) for long without
> cooking the rubber; the technology for really high-speed street tires
> doesn't exist yet."
> >>>>>>>>>
>
> WHAT?
> Better check your coffee; I think some wiseacre switched it to Dark
> Sparkling Folgers's crystals.
>
> If high speed tires "don't exist", explain the black things attached
to
> the wheels at IMSA races (national Gran Prix, 24 hours @ Le Mans)? Or
at
> the Indy 500? Or at every rebel-flagged NASCAR race?
>
> Same technology as the flying sleigh that comes around once a year?
>
> These racers routinely hit 180 mph for hours, and are at times in the
> 200+ mph range. Tires were not the limiting factor when
> NASCAR limited
> carburetion to reduce speeds that were creeping up to 230.
>
> Bringing your ideas to life,
>
> G. Matthew Bulley
> Bulley-Hewlett