Vehicle Covered in this Guide
2005-2012 Porsche Cayman, Cayman S, Cayman R, Boxster, Boxster S, Boxster Spyder. Fitment is identical between all models.
Chassis Introduction
With the introduction of the Cayman, the first fixed hardtop mid-engine car from Porsche was born. Porsche engineers created a proper track weapon with excellent structural rigidity, balance, and a potent powertrain to back it up. This chassis can support lower offset rear wheels due to its strut rear suspension, so their wheel specifications are unique amongst the other Porsche chassis.
| Bolt Pattern | Thread Pitch | Center Bore |
| 5x130mm | M14x1.5mm | 71.6mm |
OEM+ Fitment
This fitment is a small yet meaningful step up in width from the stock 18" wheels, offering a noticeable improvement in the performance and aesthetic department. It is ideal for the driver who wants to upgrade to a no-nonsense direct bolt-on fitment, with no modifications required. By increasing wheel width by ½" up front and 1" on the rear compared to the stock configuration, these wheels offer superior sidewall support for either re-using stock tire sizes or for enthusiasts who want to go with "+1 tire sizing" (245 front / 275 rear). Whether you are replacing the stock 18" wheels or downsizing from larger diameter 19" wheels to open up more cost effective tire options, this wheel setup is not only wider, it will also reduce weight (rotational mass).
Wheels
- Front: 18x8.5" ET50 // Rear: 18x10" ET36
- Popular Fitment
Tires
- APEX Staff Pick: Front: 245/40-18 // Rear: 275/40-18
- Direct Fit
- 275/35-18 rear tires can also be used
- Narrower Alternative: Front: 235/40-18 // Rear: 265/40-18
- Direct Fit
- Factory Tire Sizes
- Shorter Alternative: Front: 245/35-18 // Rear: 275/35-18
- Direct Fit
- 2020 PCA SpecCayman tire sizes
- Wider Alternative: Front: 255/35-18 // Rear: 275/35-18
- Typically a direct fit, but may require a small amount of negative camber up front to prevent rubbing if the tire model used runs really wide
- With this tire setup, we strongly recommend using the 18x9" ET46 front wheel for superior sidewall support, see HPDE/Race fitment category below.
Aggressive Street/HPDE Fitment
This staggered fitment is very similar to the one above featuring the same wheel widths, however the front wheels have a more aggressive offset which ultimately place them 8mm closer to the front fenders. This fitment is ideal for enthusiasts looking for a flush fitment closer to the fender edge with street tires, or for performance driving enthusiasts who have the ability to dial in negative camber with wider track compounds. This fitment also provides 8mm of additional brake caliper to spoke clearance.
Wheels
- Front: 18x8.5" ET42 // Rear: 18x10" ET36
- Popular Fitment
Tires
- APEX Staff Pick: Front: 245/40-18 // Rear: 275/40-18
- Direct Fit
- 275/35-18 rear tires can also be used
- Narrower Alternative: Front: 235/40-18 // Rear: 265/40-18
- Direct fit
- Factory tire sizes
- Shorter Alternative: Front: 245/35-18 // Rear: 275/35-18
- Direct Fit
- 2020 PCA SpecCayman tire sizes
- Wider Alternative: Front: 255/35-18 // Rear: 275/35-18
- Typically a direct fit, but may require a small amount of negative camber up front to prevent rubbing if the tire model used runs really wide
- With this tire setup, we strongly recommend using the 18x9" ET46 front wheel for superior sidewall support, see HPDE/Race fitment category below.
HPDE/Race Fitment
This fitment is best suited for weekend track warriors and competitive club racers looking to maximize grip and overall performance. 9” front wheels provide superior sidewall support over the more "generic" 8.5" front wheel option, which allows drivers to extract the most performance and longevity out of a given tire compound. Wider front wheel's and tires dramatically improve the cars ability to turn into the corners, and it mitigates unwanted understeer.
While the 9" wheels aren't very difficult to fit under the front fenders, there are many different tire sizes and compounds that can be used, many of which will require negative camber to prevent rubbing the fenders under suspension compression. See high-level notes under each tire combination below, or contact one of our Porsche Product Experts by submitting a fitment request form to have a more detailed one-on-one conversation about your track/race car.
* This fitment is perfect for Spec Cayman racers who want to stay in compliance with class rules.
Wheels
- Front: 18x9" ET42 // Rear: 18x10" ET36
- Popular Fitment
Tires
- APEX Staff Pick: Front: 245/40-18 // Rear: 275/40-18
- Typically a direct fit, but we encourage negative camber to prevent rubbing upon suspension compression with wider compounds, and to maximize performance and tire longevity.
- 275/35-18 rear tires can also be used
- Shorter Alternative: Front: 245/35-18 // Rear: 275/35-18
- Typically a direct fit, but we encourage negative camber to prevent rubbing upon suspension compression with wider compounds, and to maximize performance and tire longevity.
- 2020 PCA SpecCayman tire sizes (Hankook C51 medium slick compound)
- Wider Alternative 1: Front: 255/35-18 // Rear: 275/35-18
- Typically a direct fit, but we encourage negative camber to prevent rubbing upon suspension compression with wider compounds, and to maximize performance and tire longevity.
- Wider Alternative 2: Front: 255/35-18 // Rear: 285/35-18
- Typically a direct fit, but we encourage negative camber to prevent rubbing upon suspension compression with wider compounds, and to maximize performance and tire longevity.
- Wider Alternative 3: Front: 245/35-18 // Rear: 295/30-18
- Wider Alternative 4: Front: 255/35-18 // Rear: 295/30-18
- Wider Alternative 5: Front: 245-645-18 // Rear: 305-660-18
- Wider Alternative 6: Front: 265-645-18 // Rear: 305-660-18
Big Brake Kit Clearances
The following brake setups have been tested and confirmed to clear:
- Brembo 1M1.9004A1, 380mm 6-pot - fits 18x8.5" ET42 & 18x9" ET46 only.
- Brembo 1B1.9016A1, 355mm 4-pot - fits all
- Brembo 1P1.8503A1, 365mm 4-pot - fits all
- AP Racing 13.01.0054, 355mm 4-pot - fits all
- StopTech 83.788.6700.51, 355mm 6-pot - fits all
Please email or call us with any other questions related to brake clearance and we’ll be happy to help.
Still have questions?
Fill out our Fitment Recommendation form
Call us: 925-245-0773
Email us: [email protected]