2025.2

Added

• Allow lug nuts and studs in Stock Class and Free Modifications
• Allow wheel spacers in Free Modifications
• Added Michelin Primacy 4 (new OE tire for 2025)
• Added Armstrong Blu-Trac Race tire for 2 pts
• Added Hoosier TrackAttack Pro for 3 pts

Changed

• Include bump stops in non-OEM springs
• Include packers in pointed dampers
• Clarified championship tiebreak countback only considers a driver's best 7 results
• Significant changes to Touring class: Maximum 7 mod points and no balance of performance
• Continental ExtremeContact Force (ECF) tires are now 2 points
• Handicap for Buttonwillow Circuit Stock Class is now 2.0 seconds
• Clarify STI and TRD lowering springs are not considered OE
• Add weight limit for Stock class axle-back exhausts

Removed

• H&R camber bolts removed from Stock rear camber allowed parts list

2025.1

Added

• Registration deadline and provisions for late registration
• Unedited onboard videos may be permitted as a lap timing method
• Tiebreaker for identical lap times in an event
• Explicitly defined class changing rules
• Tiebreaker for identical Championship Points
• Explicitly defined protest proceedures
• New Stock Class handicap for Buttonwillow Raceway #1 and Buttonwillow New Track
• Allow catch cans in Stock class
• Explicitly allow high-octane gas
• Rear camber modifications now allowed in Stock Class
• Calculate new tracks/configurations Touring Class Adjustment Factor immediately following the event
• Yokohama Advan Apex V601 are now 0 pts
• Maxxis Victra VR-1 are now 2 pts
• Maxxis Victra VR2 are now 3 pts
• Transmission and diff cooling now allowed as Free Modifications
• Pointed modification for FA20 to FA24 engine swap
• Added illustrations for defining the leading edges of the front and rear bumpers
• Explicitly allow small rear diffusers, side skirts, and rear spats in Free Modifications

Changed

• Allow in-season rules changes that make the rules more permissive to take effect immediately
• Minimum weight for Street Class changed to 2,800 without driver and with full tank of gas
• Clarified language for allowed brake modifications
• Changed Stock Class permitted exhausts to a list of allowed parts
• Touring Class Time Handicap is now based on Street Class records and allows 3 free points
• Changed points for forced induction and tunes to reduce complexity while maintaining the same point values
• Simplified language for splitters/lips
• Underbody aero between the front and rear axles are now included in the 0.5 pt larger rear diffuser modification
• Expanded Free Modifications for suspension geometry
• Pointed suspension upgrades are now a la carte

Removed

• Camber plates no longer allowed in Stock Class
• GT Radial Tire Contingency terms and conditions are no longer discussed in rules
• Maxxis VR-1 S2 are no longer pointed