The SCCA has set up separate classes for different cars based upon their abilities and modifications. As a general rule of thumb, the more modifications you do to your car, the higher up into the list of classes it will go. This guide is designed to help you determine where your car might be classed, but does not contain additional allowances and restrictions mentioned within the Official SCCA Solo Rule Book. If you know what has been done to your car, chances are that one of our members can help you determine where your car belongs.

Special Classes

These are classes that may or may not be unique to the SRRSCCA region.

Novice – This class is designed to cater to new drivers looking to get their feet wet. There’s a special walk around the course with an experienced club member, who will give you tips/pointers, and let you know what you need to do. The members in the neon vests can also hop in and ride along with you to guide you along the way, if you need help. This class is designated with the letter “N’.

Open – This class is for drivers looking for more competition than they would otherwise have in their standard class, and is designed to train drivers for the format used at divisional and national tour events. Only the first three runs of each event count towards the season end point totals for this driver group, and they are calculated upon PAX times. For an explanation on PAX and its calculations, please see this page. Cars will be marked with their standard class abbreviation, prefixed with an “O” (ex: OSS, OSTS, OSTR).

IMS – This class was created for the Idaho Motorsports group, for those who have already made extensive modifications to their cars without the intent of building to a certain class’s specifications. The only requirements for this group are that the car must be street legal, and it must be using tires that have a tread-wear rating of 200 or higher. This class is designated with the letters “IMS”.

Standard Classes

These are the most basic “layers” of classes that are found within the SCCA solo rule book. Each of these are further split into separate classes with a different letter designation, to help level the playing field, based on a car’s natural performance ability. For example, a stock C5 Corvette would be in “A” street (AS), while a base Honda Civic would be in “H” street (HS). Please note, all/most cars are already classified within the rule book, but their level of modification changes their placing within the groups found below.

Street (formerly Stock) – Many street class cars serve double-duty as weekend racers, while still remaining weekday commuters. With competitors having theoretically equivalent equipment, the main variable becomes the driver. Vehicles must remain near stock condition except for these basic modification allowances:

– drop in air filters
– cat-back exhausts
– stock wheel sizes
– tires with minimum tread-wear rating of 200
– brake pads, braided brake lines
– shocks may be revalved/replaced/upgraded, ride height & spring must stay stock.
– either the front OR rear sway bar may be upgraded
– removed spare tire and tools
– trailer hitch, safety equipment
– aftermarket gauges, stereo equipment

Street-R (formerly Stock) – This is the same as Street, however, any DOT legal tire (including r-compounds ) are permitted.

Street Touring – The street touring classes are intended to allow common affordable modification, while keeping the cars much more “streetable” than a flat-out “Street Prepared” car would be. All of the rules and allowances of the Stock classes apply, with the following additions:

– air intake modified up to throttle body
– full exhaust modifications permitted (cats must be retained, may be replaced with high flow cat in factory location)
– factory emission & OBD equipment must be retained
– engine mount replacement
– underdrive pulleys
– ECU may be reprogrammed (except boost level)
– tires with minimum tread-wear rating of 200 (each ST sublevel class has varying wheel and tire width allowances, see rulebook)
– any brake pad, rotor, or caliper
– any shock, spring, or sway bar
– strut bars may be added, but only connect at two points
– camber plates and bolts
– OEM offered bumper lips/spoiler/aero
– replacement seat (minimum 25 lb)
– lightweight battery, A/C removal

Street Prepared – The street prepared classes offer a few more modifications than the street touring classes, in particular, slick tires (r-compounds) are re-allowed. All of the rules and allowances of stock and street touring above apply, with the following additions:

– boost levels may be modified (stock turbo)
– cat delete
– any wheel or DOT legal tire, r-compounds
– fenders may be cut or bent for tire clearance
– update/backdate parts from different year models of the same vehicle
– any seat replacement
– steering wheel replacement
– aftermarket splitters and spoilers

Street Modified – The street modified classes are intended to be the ultimate street-legal racing machines. All of the rules and allowances of stock, street touring, and street prepared above apply, with the following additions:

– any engine is allowed, with any modifications
– make of engine block must match make of original engine or chassis
– minimum weights are listed within rulebook
– sub-classes are separated based on number of seats/doors/car type/drivetrain type (two seater, coupe, sedan, FWD/RWD)
– aftermarket hoods or trunks
– wings may be added, removed, or modded
– rear seats removed

Prepared – The prepared classes move beyond the realm of “street” cars, and into the realm of pure racing vehicles. Extensive modifications are allowed, many of which may not be mentioned here. There are also additional restrictions on a per-class basis which are not outlined here:

– extensive internal and external engine modifications allowed
– maximum of 12″ wide wheels, any tire
– brakes unrestricted, but no inboard brakes unless originally equipped
– unrestricted suspension modifications
– open top cars must have a roll bar
– extensive weight reduction allowed, stripped interior
– rear seats removed
XP additions:
– pedals, steering wheel, and seat must be entirely left (or right) of vehicle center
– any engine may be used, provided it’s basic orientation and position remain the same
– minimum weights apply

Modified – The modified classes contain the fastest vehicles. These are one-off, custom built machines with the sole purpose of completing a solo course as quickly as possible. In modified, the rule set varies based upon the class, mainly depending upon weight, vehicle type, and engine size.


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