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I promised I'd report back with actual data to help people make decisions with these tires, since forums are frequently a place with no closure to a question. In short the R7's lasted 2 days at Thunderhill bypass, with the rears eventually cording and the fronts not far behind. The car is a 991.1 GT3RS with the 19" Hoosier R7's with additional camber front and rear. Both days were very hot with ambient ~104 deg F and a track temp of 140 and 125 deg F. The tires did approx 120 laps or 342 miles. Attached is a histogram of my lap times. They range from I think fast-ish to dawdling.
I promised I'd report back with actual data to help people make decisions with these tires, since forums are frequently a place with no closure to a question. In short the R7's lasted 2 days at Thunderhill bypass, with the rears eventually cording and the fronts not far behind. The car is a 991.1 GT3RS with the 19" Hoosier R7's with additional camber front and rear. Both days were very hot with ambient ~104 deg F and a track temp of 140 and 125 deg F. The tires did approx 120 laps or 342 miles. Attached is a histogram of my lap times. They range from I think fast-ish to dawdling.
Very helpful information.
What camber and toe settings are you running on the 991.1 GT3RS? My old 991.1 GT3RS needed more static camber on Hoosiers than my .2 GT3RS (big difference). What are your target hot pressures front/rear? Hoosiers like lower pressures than what the website recommends, but not to low to avoid cording both the inside/outside edges.
For the general public, R7 are not done after two days, the scenario above applies to 120 laps at Thunderhill 3-mile course with bypass, most of the lap times will be over 2 minutes (due to traffic, heat soak, tire temps, etc.). This is in excess of 250 minutes of track time, and most common DE events, you would need 3 days to cover 250 minutes of track time.
R7 don't work well on very hot weather, after a few laps they fall off. Any track day in the upper 90s F for air temperature, I don't waste them and put a set of scrub Pirelli DH (handle heat just fine, but I only get one day from them).
...avoid Michelin Slicks. 2 HC then fall off, 4 more HC at R7 pace and then to dumpster.
I'd have to check what alignment settings we were running. The shop had installed some aftermarket piece to get more camber out of it though. Hot tire pressures were a bit inconclusive so I don't want to lead people in the wrong direction. We were anywhere from 30-35 as they would air up wildly. When they finally stabilized in the afternoon, the track was too hot to make any good time on.
Your point for the general public is right on. Hoosiers should last for two days just fine, although I did run mine to the cords, instead of being heat cycled out. I think we put 12 heat cycles on them. I was extremely impressed with how stable the tires were with heat cycles. I was still able to run a 2:01 lap time on the 12th heat cycle, with the tires almost at the cords. This is in sharp contrast to the Sport Cup 2 R's that fall off 8+ seconds after 4 heat cycles.
I can also see your point about not working in hot weather, the tires certainly got greasy after hard laps. They were able to be run gently and cooled back into operating range for additional track time though.
06-21-2019, 12:30 PM
