USRA rules
Body measurements and a 3D car for every 2026 USRA class, and the Stock Car rulebook in plain English.
Unofficial and not endorsed by USRA. USRA's own 2026 rules have the final say, not this page. For a ruling, call USRA tech at 515-835-9946.
Body rules by class
- Stock Car 31 measurements Wheelbase: 107.5 in min. 31 measurements. Full-body U.S.-made passenger car on a full frame or unibody.
- Late Model 46 measurements Wheelbase: 103 in min. Car weight: 2,300–2,350 lb min. 46 measurements.
- Modified 73 measurements Wheelbase: 108 in min. Car weight: 2,400–2,500 lb min. 73 measurements.
- B-Mod 62 measurements Wheelbase: 108–112 in. Car weight: 2,500 lb min. 62 measurements. Modified with a flat deck and straight-edged sail panels.
- Limited Mod 64 measurements Wheelbase: 107–109 in. 64 measurements. Modified on a GM metric frame; a braced rear spoiler is optional.
- Factory Stock 33 measurements Wheelbase: 107.5 in min. Car weight: 2,950 lb min. 33 measurements. Stock-appearing U.S.-made passenger car on a stock full frame or a Chrysler or Ford unibody.
- Hobby Stock 35 measurements Wheelbase: 107.5 / 110 in min. Car weight: 2,950 lb min (AR). 35 measurements. Steel-bodied stock car on a full frame or unibody.
- Tuner 19 measurements Wheelbase: 107 in max. Car weight: 2,300 lb min. 19 measurements. Front-wheel-drive compact on an unaltered, OEM-appearing body.
Rulebooks in plain English
- Stock Car 263 rules, with 8 errors in the official text fixed and 24 rulebook conflicts marked.
Official rulebooks and rulings
The official rulebooks are on usraracing.com. For a ruling, call USRA tech at 515-835-9946 or email tech@usraracing.com.