The 718 Cayman and Boxster are about balance. With the engine sitting behind the driver and ahead of the rear axle, the front end reacts to every change you make at the corners, and wheel diameter is one of the biggest changes you can make. For the 5-lug Base, S, T and GTS cars, the choice comes down to two setups: a 20-inch street fitment or a 19-inch track fitment.
The two setups side by side
Both use the same rear width and offset, and the 19-inch front matches the wider of the two 20-inch front options. What changes is the diameter, the sidewall and the tires you can run.
| 20" Street | 19" Track | |
|---|---|---|
| Front wheel | 20x8.5 ET42 or 20x9 ET42 | 19x9 ET42 |
| Rear wheel | 20x10.5 ET45 | 19x10.5 ET45 |
| Primary tires | 235/35R20 F, 275/30R20 R (street) | 245/35R19 F, 285/30R19 R (200TW) |
| Wider option | 245/35R20 F, 285/30R20 R (performance) | 255/35R19 F, 295/30R19 R (R-compound) |
Why 20 inches on the street
The 20-inch setup is built for street cars where looks and ride on smooth roads come first. ET42 up front sits flush with the fender lip at stock height with no bodywork, and the bigger diameter shows off spoke design and deep concavity. Weight still matters here: a forged 20-inch front wheel can be 3–4 kg lighter than the factory cast wheel, and on a mid-engine car you feel that right away in how quickly the nose turns in.
Why 19 inches on track
Dropping to 19 inches takes another 1.5–2 kg per corner off compared with a 20-inch wheel, which cuts both unsprung and rotating mass. The taller sidewall gives the tire more room to deflect, so it handles curbs and rough track surfaces better. The 718 is one of the lightest modern Porsches, so this is where the car gets the most out of the change: sharper steering, shorter stops and quicker direction changes.
Fitment details that apply to both
- Bolt pattern is 5x130 with a 71.6mm center bore and ball-seat lugs, torqued to 130 Nm (96 ft-lb).
- Stock hub depth calls for a 27mm shank lug bolt. Add spacer thickness to that (a 5mm spacer means a 32mm shank), and never run fewer than 8–10 full threads of engagement.
- These sizes are for the 5-lug Base, S, T and GTS. The GT4 and Spyder have a 40mm wider rear track and need an 11-inch rear, and the RS models use Center Lock hubs, so neither shares these specs.
Which one to pick
If the car is mostly a road car and you want the stance, go 20 inches. The setup fits flush with no modifications and still takes weight off the front axle. If you are doing track days, the 19-inch setup is the better tool: lighter, more forgiving over curbs, and sized for 200TW and R-compound tires. Since the rear width and offset are the same across both, one option is to run the 20s on the street and keep a set of 19s on track tires for event weekends.