The second-generation GR86 and BRZ weigh about 2,800 lbs and make their speed in the corners. That makes wheels one of the most noticeable upgrades you can make. The main decision is diameter: 18 inches for the street, or 17 inches for the track.
18x9.5: the street setup
An 18x9.5 ET38 square setup fills the fenders without much extra unsprung weight. It fits a 255/35R18 tire, nearly 20% more contact patch than the factory 215. The car puts power down better out of corners and gives more steering feedback. Offsets from ET35 to ET40 work; much below ET30 you'll be rolling or modifying fenders.
17x9: the track setup
For autocross, track days and time attack, 17x9 ET35 is the standard. A forged 17x9 can come in under 16 lbs, versus 22+ lbs for the factory 18-inch wheel. That's more than 6 lbs saved at each corner, which a car this light feels right away. The taller 40-series sidewall also takes curbs better and is more forgiving while you learn the car's limits. Run 245/40R17 or 255/40R17 tires.
How to choose
| 18x9.5 ET38 | 17x9 ET35 | |
|---|---|---|
| Best for | Daily driving, canyons | Track, autocross, time attack |
| Tires | 245/40R18 or 255/35R18 | 245/40R17 or 255/40R17 |
| Sidewall | Sharper, firmer | More compliant over curbs |
Both setups are square, so you can rotate tires either way. One warning: the GR86 and BRZ use a 5x100 bolt pattern, not the 5x114.3 of the WRX and STI. Don't buy wheels meant for those cars.