These tractors have a maximum engine size of 466 cubic inches, one turbocharger 3" on the intake 4" on the exhaust, intercoolers, and a maximum tire size of 24.5" x 32". The difference in the two class is the weight and pump. The 7700 pound class is limited to an A pump. The 7800-pound class is limited to a P pump.
These 6400-pound stock looking trucks are limited to a maximum engine size of 510 cubic inch limit with 1 percent allowance, must run single 4 barrel carburetor, must be naturally aspirated - no blowers, no nitrous or nitrous accessories allowed on truck, no aluminum engine blocks are allowed, no Pro Stock style or Hemi heads allowed- must accept stock intake with no major modifications, intake manifolds will be limited to a single plane CAST Intake that is readily available to the general public. The maximum tire size is 14.50" x 36" and DOT approved. No cutting or grooving allowed.
These 8500 pound tractors can run a maximum engine size of 540 cubic inches tractors, a turbo charger, and a maximum tire size of 24.5" x 32". NTPA LPS can run a “P” pump 3000 or 7100 series only (only one plunger per cylinder).
These 10,000-pound tractors are limited to a 540 cubic inches, a "P" pump of 13 mm. Intercoolers and water injection allowed. The maximum tire size is 24.5” x 38”. Interstates Pro Farm class is limited to "A" pump on the injection.
These truck must run a truck body, weigh 6200 pounds, with a maximum 575 cubic inch engine limit. They can be turbocharged or supercharged engines running alcohol fuel. The tires are limited to 18.4" x 16.1".
These 8000-pound trucks must run Must run a single turbo. 6.4 liter Power Stroke engines may utilize the factory twin-turbo configuration. 3.0 smooth bore turbos will be allowed to run. Must be an engine that was available in a 1-ton diesel pickup. Open Drivelines are permitted. No fiberglass body parts with the exception of the hood and tailgate. Tires must be DOT approved and limited to 35" X 12.50" max tire size (No cutting or grooving) and duals on the rear are allowed.