Classing your car appropriately can be a daunting task when you don’t even know where to start. This guide is intended to give you a good idea of where you should be, but may not be fully up to date with the current rulebook. For the current rules, check https://www.scca.com/pages/solo-cars-and-rules.
Whether you are going to your 1st event or your 100th event, you will need to know what class your car falls into. Regions are allowed to run non-standard classing to better serve the local membership, so it’s always a good idea to know where you’d fall within national classing to make things easier when visiting other regions.
The SCCA offers several classes in different groups in an effort to give most popular cars a place to compete, regardless of modification levels. The number of classes can be confusing at times though, so let’s break it down a little. There are groups based on allowed modifications (NOTE: The rulebook is a list of allowances, so if it doesn’t explicitly say you *can* do something, then you cannot). Those groups are:
- Street Touring
- Street Prepared
- Street Modified
- Xtreme Street
- Classic American Muscle
- Solo Spec Coupe
Each of those groups is broken down into classes that include specific cars, with the hopes that the cars in a class are roughly competitive with each other. Let’s talk about what’s allowed for each group.
Street is the most limited class. You are allowed to change 1 sway bar, and you can change your wheel size by 1″ in diameter either way, but you must maintain the OEM width. You can run any shock that is of OEM type, and any brake pad material. Tires must be 200TW minimum.
Street is broken down into SS, AS, BS, CS, DS, ES, FS, GS, and HS. Classes generally flow from the “fastest” to the “slowest”, so SS has cars like the 911 GT3, and HS is for stuff like base model Civics.
The allowed modifications list in the rulebook starts getting pretty long and involved, so from this point forward, I’m just going to list major things. Please consult the rulebook for more information.
Street Touring opens up modifications for suspension, tuning, wheels, brakes. So, you can do any shock/spring/coilover that bolts in the OEM location, any sway bars, any exhaust (must have a cat), wheels are limited by width (for example, STS is limited to 7.5″ wide wheel), any brake setup is allowed. ECU tuning is allowed, with some restrictions (stand alone systems for pre OBD2 only). 200TW tires minimum.
ST is broken down into STS, STX, STU, STR, and STH.
Street Prepared can be thought of as “Street Touring + Race Tires”. Wheels are unlimited. Tires must be DOT-Approved, but no treadwear minimum.
SP is broken down into SSP, ASP, BSP, CSP, DSP, ESP, and FSP.
Street Modified opens up engines – swaps and building (internals, adding forced induction). Body work can be altered. Aero is allowed. There is a lot more to it, to if you find yourself interested in this class, check the rulebook.
SM is broken down into SSM (2 seaters) , SM and SMF (FWD).
Xtreme Street is a recent addition. It’s basically an unlimited street tire class, so long as you have a full interior and 200+ treadwear tires.
XS is broken down into XSA (heavier cars) and XSB (lighter cars)
Classic American Muscle
Unlimited street tire class for RWD American cars. Must have a full interior and 200+ treadwear tires.
CAM is broken down into CAM-S (sports cars), CAM-C (contemporary cars, post 1987?) and CAM-T (traditional, pre 1987?)
Solo Spec Coupe
Solo Spec Coupe was designed as a spec class for the 2013-2016 FRS/BRZ. You can run the car 100% stock, or you can change the bits in the SSC package from Tire Rack, but you can not make any other change to the car. Wheels must be OEM size and weight. Tires must be the current spec, which as the writing of this is the Falken RT660.
Prepared is where you end up when you want to gut the interior. Class allows ANY race tire.
Modified is for non-car based race cars, like Formula Ford, Formula Vee, F500, etc.