Classes

Modified Tractor- The class began as farm tractors with non-tractor engines and grew into fully custom machines with multiple engines and power plant types. All divisions of the Modified class use a maximum of a 20” drawbar and 30.5 x 32 tires.

Modified (RN)- 7,500 pounds, 3 blown automotive engines with 8-71 blowers, 2 blown automotive engines with 14-71 blowers, 1 or 2 Allison aircraft engines (based on blower type), 1 industrial or marine engine 12 cylinder limit, combination of NTPA recognized turbine engines not to exceed a maximum of 5050 total horsepower and other combinations.

Light Unlimited (GN)- 6,000 pounds, no turbines.

Modified (GN)- 7,500 pounds, 4 blown automotive engines with 8-71 blowers, 3 blown automotive engines with 14-71 blowers, 2 Allison aircraft engines, 2 industrial or marine engine 12 cylinder limit, combination of NTPA recognized turbine engines not to exceed a maximum of 5800 total horsepower and other combinations.

Unlimited (GN)- 8,000 pounds, any power plant making weight.

Super Stock Tractors- Diesel or alcohol powered, multiple turbo chargers. Heavy Super Stock tractors at Regional level will run 20” drawbar with the weight at 8000 for alcohol and 8300 for diesel. Light Super Stock Tractors at RN level only will run component tractors at 6200 lbs. and the agricultural rearend tractors at 6500 lbs. Grand National Open (Alcohol) and Diesel (Diesel fuel only) tractors run with a 20” drawbar and weigh 8000 pounds. The Grand National Light Super Stock class has a mixture of fuels, run at 6200 lbs. and put a a wild show due to the high horsepower to weight ratio.

Pro Stock Tractors- Single turbo charger diesel only tractor class. 10,000 pounds, 20” drawbar, 680 cubic inch displacement limit, 1 turbo charger, 24.5 x 32 tires, water injection and/or intercoolers allowed.

Light Pro Stock Tractors- All rules from Pro Stock class plus 540 cid limit, no component chassis, engine heads must be OEM agricultural-type for brand (no billet), no overhead cams, no inner/after coolers, “p” pump 3000 or 7100 series only (only one plunger per cylinder). 8500 pounds.


Limited Pro Stock Tractors- All rules from Pro Stock class plus 640 cid limit, no component chassis, engine heads must be OEM agricultural-type for brand (no billet), no overhead cams, no inner/after coolers, “p” pump 3000 or 7100 series only, maximum 2 valves per cylinder, turbo limit: 4.1 inlet smooth bore housing. 9500 pounds.

Super Farm Tractors- Limited single turbo charger diesel only tractor class. 9300 pounds, 20” drawbar, 640 cubic inch displacement limit, 1 turbo charger 3x3” (sealed after inspection), 24.5 x 32 tires, “p” pump, water injection allowed. No after/inter coolers or overhead cams.

Modified Mini Tractors- High power to weight ratio, offers exciting rides. Powered by automotive style or turbine engines. 2050 pounds, 18” drawbar, 18.4x16.1 tires. Turbines limited to NTPA 1800 horsepower rating, 575 cid blown or 650 cid naturally aspirated limits.

Four Wheel Drive Trucks- Stock appearing 4x4 truck, 6200 pound, 650 cid limited naturally aspirated engine, 112 inch circumference and 20 inch wide rim tire limit, 26” drawbar.

Super Modified Four Wheel Drive Trucks- Stock appearing 4x4 truck, 6200 pound, 500 cid limited supercharged or turbocharged engine, 112 inch circumference, 20 inch wide rim tire limit, 26” drawbar.

Diesel Pro Stock Four Wheel Drive Trucks- Stock appearing 4x4 truck (most street-like class), 8000 pound, diesel fuel only, 460 cid limit with a maximum 3.0” turbocharger, “p” pump, DOT tires (35” maximum), and 26” drawbar.

Super Stock Diesel Four Wheel Drive Trucks- Stock appearing 4x4 truck, 7500 pound, diesel fuel only, 460 cid limit, limited to 2 stage configuration of turbochargers, water injection allowed, “p” pump, maximum tire 35” tall with tread not to exceed 18”, and 26” drawbar.

Two Wheel Drive Trucks- Truck body, 6200 pound, 575 cid limit, turbocharged or supercharged engines, alcohol fuel, 18.4 x 16.1 tire, 30” drawbar.

Super Semi- Stock appearing semi with single or multiple turbochargers. 20,000 pounds, 16” drawbar, diesel fuel only, DOT approved tires. Engine must be from a production-available commercial truck with minimum of 500 units produced. Up to two stages of pressure allowed in turbocharger system.

Pro Stock Semi- Stock appearing semi with single turbocharger. 20,000 pounds, 16” drawbar, diesel fuel only, DOT approved tires. Engine must be from a production-available commercial truck with minimum of 500 units produced. One turbocharger, any size.




Contact Info

  • ADDRESS:
    National Tractor Pullers Association
    6155-B Huntley Road,
    Columbus, OH 43229
  • PHONE:
    (614) 436-1761
  • FAX:
    (614) 436-0964
  • WEBMASTER EMAIL