Porsche ships the 992 GT3 on a 20-inch front and 21-inch rear. On the street that's hard to beat. On track, the 21-inch rear is a problem: most 200TW and R-compound tires are built around 18 to 20 inch diameters, so wide 21-inch track tires are hard to find.
The street setup
For street and canyon driving, we keep the factory proportions: 20x9.5 ET50 front and 21x12 ET48 rear, with 255/35R20 and 315/30R21 tires (or 265/325 for more grip). The 992's double-wishbone front suspension has tighter clearances than the 991's strut, so front offset needs to be exact.
The track setup
For regular track use, drop the rear to 20 inches: 20x9.5 ET50 front and 20x12 ET45 rear. That opens up tires like the Nankang AR-1, Goodyear Supercar 3R and Michelin Cup 2 in wide 325–335 rear sizes. You also gain a little sidewall for curb strikes.
| Street (20/21) | Track (20/20) | |
|---|---|---|
| Front | 20x9.5 ET50 | 20x9.5 ET50 |
| Rear | 21x12 ET48 | 20x12 ET45 |
| Tires | 255/35R20, 315/30R21 | 265/35R20, 325/30R20 |
What about 19s?
Some steel-brake cars run 19-inch square for slicks, but clearance around the rear suspension is tight. We treat 20 inches as the safe minimum. Every 992 GT3 is center lock (84 mm bore, 450 Nm), so a track set needs to be built as center-lock wheels too.