997.2 Cup tyre size range / possibilities
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From: Ormond Beach, Fl
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From: Danbury, CT, USA
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From: Midwest - US
9J x 18 ET43 (1” OUTER X 8” INNER)
11J x 18 ET30 (2.5” OUTER X 8.5” INNER)
997.2
9.5J x 18 ET37
12J x 18 ET30
7.1's are narrow body tubs, 7.2's are wide body (wider front and rear).
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From: SF Bay Area, CA
Bringing this thread back from the dead. Did anyone try?
The why, I have access to 991 take offs from my other car that I race and want to run on my non raced 997.2
The basics the 997.2 and 991 run a 12" wide rear rim, so the 991 wider 31/71 tire fits the rim. Not so worried about the 1cm wider tire fitting, however it is a 71 profile vs 68, so 3cm taller tire so the car will sit 1.5cm higher. The 3cm larger rolling radius will result in taller gearing, slower acceleration, and the dampers may need some tuning to compensate the taller sidewall. The taller sidewall may present clearance to wheel well issues. Now this is the key point brought up by the OP and @analogmike and @THJR Can someone please post a pic of the Grand AM wheel well modifications or DM me 🙏
The 997.2 front rim is 9.5" vs 10.5" on the 991, the outer lip can be widened and I have 2.5" outers to make a 10.5" rim. Not sure if the front fender will accommodate an extra inch outward but it does seem the 10.5" is the perfect width for the 991 27/65 tire. Anyone ran on a 10" rim with 27/65 tire on a stock 997.2?
Most interested in seeing some pics of the needed rear wheel well mods and if any mod needed on the front.
🙏
The why, I have access to 991 take offs from my other car that I race and want to run on my non raced 997.2
The basics the 997.2 and 991 run a 12" wide rear rim, so the 991 wider 31/71 tire fits the rim. Not so worried about the 1cm wider tire fitting, however it is a 71 profile vs 68, so 3cm taller tire so the car will sit 1.5cm higher. The 3cm larger rolling radius will result in taller gearing, slower acceleration, and the dampers may need some tuning to compensate the taller sidewall. The taller sidewall may present clearance to wheel well issues. Now this is the key point brought up by the OP and @analogmike and @THJR Can someone please post a pic of the Grand AM wheel well modifications or DM me 🙏
The 997.2 front rim is 9.5" vs 10.5" on the 991, the outer lip can be widened and I have 2.5" outers to make a 10.5" rim. Not sure if the front fender will accommodate an extra inch outward but it does seem the 10.5" is the perfect width for the 991 27/65 tire. Anyone ran on a 10" rim with 27/65 tire on a stock 997.2?
Most interested in seeing some pics of the needed rear wheel well mods and if any mod needed on the front.
🙏