The Porsche guys around here got together and bought a container load of
Kumho radial 15X5.50 60 series tires with a nice asymmetric tread. I don't
know the details, but the tires are NOT available in the US and all the
Porsche guys say they are wonderful. They haven't volunteered to sell me
any--I wonder why.
-----Original Message-----
From: owner-fot@autox.team.net [mailto:owner-fot@autox.team.net] On Behalf
Of Tony Drews
Sent: Wednesday, August 24, 2005 4:37 PM
To: fot@autox.team.net
Subject: RE: Hoosier tire wear survey
I'm running about .5 degrees negative in the fronts (to help tire wear,
thanks for the suggestion Bill!). Rears are zero degrees camber, detroit
locker diff (basically acts like it's welded in the corner under power as I
understand it). I got 5 1/2 sessions at Blackhawk then rotated the still
decent fronts to the pretty beat up rears, and maybe 4 at Grattan before I
had to start replacing tires because I was worn to the point that at least
one of the tire grooves were essentially gone. By the end of the weekend
(6 sessions) I had replaced 3 of the 4 tires with almost worn out but still
usable tires. Probably would have replaced the 4th but wanted to keep Snook
going.
I run 26 psi front / 24 psi rear (plain old air). I bumped the rear
pressure up a psi from 23 to tame some of the oversteer in an attempt to get
more tire life. Rears wear out the inside edge first. The car has some
amount of oversteer, but I tried to not hang it out too far. I'm giving up
on Hoosiers and am going to start trying other brands. Unfortunately,
nothing is really available in 60 series so I'm forced to go to 50 series
tires (or Dunlops and add 2 to 4 seconds a lap to my times).
While I don't do the math to know what I spend a race, I'm spending over
$400 in tires alone per race weekend.
Of course, Jack knew all of this, but the rest of you didn't...
- Tony
At 11:27 AM 8/24/2005, Bill Babcock wrote:
>It would be useful to know the suspension setting for the cars that are
>gobbling tires. Also, what do you call a "worn out" tire. Is it worn
>out when you start seeing your lap times come down a bit, or are you
>driving them to the cords?
>
>I see a lot of cars on bias ply tires that are running a degree or more
>of camber, like it's some kind of rule that camber=good. If you have
>added camber by shortening the upper arm, then you have a lot of camber
>gain, so even if you set it at zero degrees, as your suspension
>compresses you get more.
>
>I'm running Peyote with zero to .5 degrees of camber, zero toe, and
>whatever caster that a TR6 lower trunnion gives (I think it's 3
>degrees). I have about 2 degrees of camber gain at full suspension
>travel (compression). The Ackerman point is about five inches before the
rear axle.
>
>Using Hoosier vintage TDs 5.50 X 15 front and rear, about 22 pounds in
>the front, 24 in the rear, nitrogen.
>
>My tires give even temps across the face and show no sliding marks--the
>wear is even across the tire. I gain about 1 second with new tires
>after one heat cycle, lose that back after ten or so cycles. After ten
>cycles there is no further degradation of lap times. I run tires to 30
>or 40 heat cycles or more. So far this season I've bought one set of
>Hoosiers to replace the ones I flat spotted when I lost my steering.
>And I bought one set of Dunlops to run Monterey.
>
>I'm going to be trying the DOT Hoosiers at the CRC. I'll let you know
>what I think of them. They are radials, so I'll need to play with camber.
|