Hoosier TD-R sizes Options

[twin356]

I will be rolling out my 914-6 2.0 vintage car this spring. Looking to understand what size rear tires to run on 8" rims. I basically geared for 24", as that is size of most 225/50/15 radials. However, in vintage (SVRA/VRG) is preferred. So, run the 24x8.5-15, or the 25x8.5-15.
What is being run by others?
Thanks
Scott

[wndsrfr]

Hi Scott...I've been racing with SVRA/VDCA/VRG/HSR for the past year and am on the Hoosier's with Kermee--2.7/6 weighing 1950#, 215rwhp and stock gearing. I'm on TDR's, 23x7.5 15 front and 24x8.5 15 rear. The car likes that setup as it's faster than the driver....Lap times at Summit Point are 1:28's mostly, one or two at 1:26 & change. Curiously, at VIR & Watkins Glen the lap times are almost identical at around 2:20 with a few at VIR at 2:18 or 2:17& change, Road Atlanta at 1:45's....
If you're any lower on power, don't go with the 25 diameter as you'll be better geared with a stock box on the 24's.....I can just barely hit my rev limiter (conservatively set at 7400) at Daytona crossing the tri-oval at about 153mph...
The Hoosiers start out at 17psi cold, finish at 22psi hot in a 30 minute session and start to fall off after 16-18 heat cycles with my level of talent.
If you're considering radials, the groups may "frown" on them unless they've got full tread--you might get by with Toyo RA1's shaved to 4/16's--I really liked them when doing DE events but am drinking the koolade with the racing groups and using Hoosiers.

[twin356]

Hi Scott...I've been racing with SVRA/VDCA/VRG/HSR for the past year and am on the Hoosier's with Kermee--2.7/6 weighing 1950#, 215rwhp and stock gearing. I'm on TDR's, 23x7.5 15 front and 24x8.5 15 rear. The car likes that setup as it's faster than the driver....Lap times at Summit Point are 1:28's mostly, one or two at 1:26 & change. Curiously, at VIR & Watkins Glen the lap times are almost identical at around 2:20 with a few at VIR at 2:18 or 2:17& change, Road Atlanta at 1:45's....
If you're any lower on power, don't go with the 25 diameter as you'll be better geared with a stock box on the 24's.....I can just barely hit my rev limiter (conservatively set at 7400) at Daytona crossing the tri-oval at about 153mph...
The Hoosiers start out at 17psi cold, finish at 22psi hot in a 30 minute session and start to fall off after 16-18 heat cycles with my level of talent.
If you're considering radials, the groups may "frown" on them unless they've got full tread--you might get by with Toyo RA1's shaved to 4/16's--I really liked them when doing DE events but am drinking the koolade with the racing groups and using Hoosiers.

Thanks for feedback. I geared car, for 24" (A,GQ,KA,Q,U). I will start with the 24's.
Power should be good. full blown 906 build. I use to race 356's , go out of Porsches for a number of years. Now ready to start again.

[wndsrfr]

Hi Scott...I've been racing with SVRA/VDCA/VRG/HSR for the past year and am on the Hoosier's with Kermee--2.7/6 weighing 1950#, 215rwhp and stock gearing. I'm on TDR's, 23x7.5 15 front and 24x8.5 15 rear. The car likes that setup as it's faster than the driver....Lap times at Summit Point are 1:28's mostly, one or two at 1:26 & change. Curiously, at VIR & Watkins Glen the lap times are almost identical at around 2:20 with a few at VIR at 2:18 or 2:17& change, Road Atlanta at 1:45's....
If you're any lower on power, don't go with the 25 diameter as you'll be better geared with a stock box on the 24's.....I can just barely hit my rev limiter (conservatively set at 7400) at Daytona crossing the tri-oval at about 153mph...
The Hoosiers start out at 17psi cold, finish at 22psi hot in a 30 minute session and start to fall off after 16-18 heat cycles with my level of talent.
If you're considering radials, the groups may "frown" on them unless they've got full tread--you might get by with Toyo RA1's shaved to 4/16's--I really liked them when doing DE events but am drinking the koolade with the racing groups and using Hoosiers.

Thanks for feedback. I geared car, for 24" (A,GQ,KA,Q,U). I will start with the 24's.
Power should be good. full blown 906 build. I use to race 356's , go out of Porsches for a number of years. Now ready to start again.

Oh yeah with that gearing you'll want the 24's for sure....looking forward to seeing you on the track....my next sessions are Zone 2 at VIR for shakedown then VDCA Wild Hare run...