Fitment guide

Porsche Spec Cayman (SPC) Wheel & Tire Fitment Guide

Originally published | 04/11/2023
Updated | 06/15/2024

Looking to get a set of wheels that fit the rule book for Porsche Club of America’s Spec Cayman class? Well, look no further as we have our class legal wheels for your 2006-2008 Spec Cayman in this dedicated guide to this amazing racing class with current options being our Flow Formed SM-10.

Brake Clearance Information

In the engineering phase of wheel development we 3D scan factory brakes and review 2D aftermarket brake templates in order to optimize our barrel profiles and spoke curvatures. As a result, our wheels offer massive brake clearance so you can run the smallest possible wheel diameter.

Available Wheel Designs

Bolt Pattern


Center Bore


Lug Seat

R14 Ball Seat

Thread Pitch


Spec Race Wheel Fitment

  • Black Porsche Cayman - SM-10 in Anthracite
  • White Porsche Cayman - EC-7RS in Race Silver
  • White Porsche Cayman - SM-10 in Custom Finish
  • Black Porsche Cayman - SM-10 in Satin Black

Spec Cayman is a PCA racing series that promotes equal competition between drivers utilizing the 2006-2008 Cayman S (3.4 liter) cars. As long as the proper S engine and transmission are installed, the non‐S (2.9‐liter model) chassis from 2007 - 2008 may also be used.

A s pec series or "one-make" series is based on a designated make/model vehicle and requires all drivers to prepare them in accordance to a predetermined set of rules. A field of identical race cars puts an emphasis on driver skill and team preparation, and with costs controlled more drivers can afford to get behind the wheel. This is some of the most exciting and competitive racing out there!

Whether you currently race in Spec Cayman, plan to join in the future, or you intend to modify your weekend track car in parity with the rulebook so you can accurately compare lap times to racers, any 987 Cayman/Boxster owner can run this approved wheel and tire configuration. In regards to wheels and tires, official rulebook states:

  • The required rims are 18x9 front and 18x10 rear or narrower.
  • Wheel/tire combined weight must be equal or exceed 40 lbs. for fronts, and 46 lbs. for rears.
  • The tread at the top of the tire may not extend out beyond the fender arch above it. This rule does not apply to the rear for rain tires as long as the spacers used are no wider than necessary to prevent rubbing.
  • Hubs may be converted to studs in place of wheel bolts.
  • Click here ( to view the complete rulebook


  • Front Wheel Size: 18x9” ET46
  • Rear Wheel Size: 18x10" ET36
    • Available in SM-10, VS-5RE & SM-10RE


  • Dry:
    • Front Tire Size: 245/35-18
    • Rear Tire Size: 275/35-18
    • Hankook Z214 C51 (40 TW)
  • Wet: Free as long as they fit on the spec legal wheels above 

Additional Resources

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