Car Class Calculator

This calculator helps you determine your class eligibility and modification points based on your modifications.

Chassis

Gen. 2 cars adhering to Stock Class rules can participate in Stock Class but will take a time handicap. Please refer to the current rules for details.

Single choice

Gen. 1 (2013-2020 model year) 0.0

Gen. 2 (2022+ model year) 2.0

Tires

For Stock and Street Class, heavy tire restrictions apply (see rules for details). Any tire not on this list will automatically be 6pts, without prior rules board approval.

Single choice

17" GT Radial SX2 / GT Radial HPY / Michelin Primacy HP -1.0

215/40R18 Michelin Pilot Sport 4 (OEM only) 0.0

18" GT Radial SX2, GT Radial SX2 RS 1.0

V730, RS-4, ZIII / ZIIISS, RT615K, 595 RSRR, CUP2 (180TW), NS2R, SUR4, AD08R, NT01 / NT05, R888, Supercar 3, CUP2 Connect, VR-1 S1, MPS4S 2.0

Super tires: CR-1, AR-1, A052, RC-1, VR-1 S2, RE71R, RE71RS, Rival S, SUR4G, RT660, Supercar 3R 3.0

Treadwear 40-99 5.0

Racing slicks 6.0

Suspension

Single choice

OEM-style, off-the-shelf, non-adjustable, non-rebuildable dampers with off the shelf valving and with OEM or equivalent springs 0.0

Adjustable dampers, non-adjustable rebuildable dampers or stiffer than OEM springs 1.0

Drivetrain

Multiple choices

Aftermarket intake, header, front-pipe, over-pipe, and/or any removal of OEM catalytic converter 0.5

Lighter than OEM or lower rotational inertia flywheel, clutch and/or driveshaft 0.5

Aftermarket limited slip differential 0.5

Aftermarket transmission 1.0

Forced induction 5.0

Engine swap (FA24) 2.0

Engine swap (other) - ask rules board for individual engine swap classing 8.0

Engine tuning

Single choice

OEM Tune 0.0

Gen. 1 NA tune for 93 or lower (R+M)/2 octane rating (Non-OEM) 0.5

Gen. 1 NA tune for higher than E15 or 93 (R+M)/2 octane rating 1.5

Gen. 2 NA tune for 93 or lower (R+M)/2 octane rating (Non-OEM) 1.0

Gen. 2 NA tune for higher than E15 or 93 (R+M)/2 octane rating 1.5

FI tune for 93 or lower (R+M)/2 octane rating 0.0

FI tune for higher than E15 or 93 (R+M)/2 octane rating 2.0

Rear Aero

Since aerodynamic mods can be varied in form/function, they may warrant individual assessment by the rules board.

Multiple choices

Really Small Rear Aero - OEM rear spoilers, OEM wings (excluding tS wing), and aftermarket spoilers, wings and gurney flaps less than 60mm in height 0.0

Small Rear Aero - aftermarket rear spoilers more than 60mm in height 0.5

Medium Rear Aero - BRZ tS, SARD LSR, or any wing with max width of 1400mm, max stand height of 200mm, max chord length of 200mm, and no added gurney flap 1.0

Large Rear Aero - APR GTC-200, Voltex Type 12, Voltex Type 1S, or any wing with max width of 1460mm, max stand height of 245mm, and max chord length of 250mm 1.5

Unlimited Rear Aero - wings with width greater than 1460mm, strand height greater than 245mm, or chord length greater than 250mm 2.0

Rear diffuser that extends in front of the rear axle or behind the rear bumper 0.5

Front Aero

Since aerodynamic mods can be varied in form/function, they may warrant individual assessment by the rules board.

Multiple choices

Small Front Aero - STI lip, TRD lip, or any device that extends less than 50mm outward or rearwards from the bottom leading edge of the bumper 0.0

Medium Front Aero - any device that extends 50 to 74mm outward or rearwards from the bottom leading edge of the bumper 1.0

Large Front Aero - any device that extends 75 to 124mm outward or rearwards from the bottom leading edge of the bumper 1.5

Unlimited Front Aero - any device that extends greater than 125mm outward, and any distance rearward from the bottom leading edge of the bumper 3.0

Canards/dive planes, hood vents, fender vents and/or any vertical deviation on splitter 0.5

Weight reduction

Multiple choices

Removal of any interior trim pieces or seating not required for installation of a roll cage 1.0

Points	-1
Class	Stock

Chassis

Tires

Suspension

Drivetrain

Engine tuning

Rear Aero

Front Aero

Weight reduction

Summary