10,500# Super-Field Tractors - Heavy & Light Classes

(rules adopted from NWMTPA 2021 Rules)

1. Maximum weight will be 10,500 lbs 

2. All weights must be securely fastened to the vehicle. 

3. Weights must not interfere with the sled or the sled chain. 

4. Rear weights cannot extend more than three inches behind the rear tires. 

5. Front weights cannot extend forward more than 13 feet from the center of the rear axle. 

6. All pulling vehicles running anywhere, whether on the track, in the staging area, or in the pit area, must be attended to within 10 feet of the vehicle by an association member, or be disqualified for that class. 

7. All drivers must remain seated while operating their pulling vehicle on the track or will be disqualified (general disqualification rule applies). 

8. All pulling vehicles must have fire extinguishers on board and in working condition. 

9. Drivers must wear a safety helmet and a single layer fire suit during competition (a full-faced helmet, helmet face shield, head sock, fire resistant gloves, and fire resistant shoes are recommended). 

10. All pulling vehicles must be equipped with a dead man throttle to bring the vehicle to idle when released. On all pulling vehicles using a roll cage, the driver must wear a full- faced safety helmet and use a four-point safety harness securely fastened to the rollcage. Helmet and safety harness must be worn during competition. 

11. Factory raps or roll cages are suggested but not mandatory. All tractors must have a strong and rigid seat that is securely fastened to the tractor. Tractors without a cage are required to have a lap belt and be worn during competition. 

12. All tractors must have stabilizer bars. The stabilizers will extend a minimum of 32 inches behind the center of the rear axle. The stabilizer pads must not be more than 10 inches off the ground. The pad must be a minimum of 5 inches square. A minimum of 20 inches will be allowed between the outermost part of the pads. Stabilizer bars must be able to hold the weight of the tractor. All tractors are required to have bumpers on their stabilizer bars that extend behind the rear wheels. 

13. All tractors must be equipped with fenders to provide protection for the drivers from the rear tires. The fenders must be strong enough to support the driver's weight.

14. All ether bottles (starting aids) must be placed outside of engine compartment. 

15. All tractors must have two extra support bars added to prevent splitting of tractor. Each support bar is mounted to the rear axle housing with at least two 5/8” bolts. Each support bar will extend forward of flywheel area and fasten to the side of the block or main frame with at least two 5/8” bolts. 

16. All tractors may have engine side shielding, but not mandatory. Those having shields are to be made of steel or aluminum and be 16 gauge or .060 thick. No factory fan blades are allowed. 

17. Diesel tractors must have air kill switches sufficient to stop engine. 

18. The kill switch fastener must not be placed over 8 inches from the centerline of the tractor. It can't be higher than 48 inches from the drawbar. The tractor weights must not interfere with operation of the kill switch. 

19. All tractors with inline pumps must have a 3 way fuel shut off system that can be activated from the driver's seat. 

20. Other than the driver, no other riders are allowed in or on the pulling vehicle at any time, whether on the track, in the staging area, or in the pit area. 

21. All tractors must have an OEM factory wide frontend, or a tech approved homemade that resembles an OEM front axle. 

22. All tractors without OEM front axles must have front axle skid plates as per diagram.

23. The skid plates must be mounted in line with each frame rail and extend from the center of the front axle forward (on both sides) equal in strength to frame rail material. Skid plate surface to be a minimum of 4 inches wide and 12 inches long with minimum 6 inches curve when measured from the front most part of rolled edge. The skid plate must be able to support the weight of the front end when checked with a jack. Maximum ground clearance is bottom of front wheel rim not to exceed 4 inches with front tires in normal operating position. (See diagram here) OR Front axle support to be made of 2.00” x.095” chrome molly tubing or 2.00” x .120” mild steel tubing or same material as tractor frame rails. (See diagram here) Front axle support should connect to each frame rail in line and extend toward front of tractor. Front skid/front axle support should have radius to prevent digging in to track. Front axle support frame should be strong enough to support front end weight of tractor. Support should have a maximum of 4” ground clearance.

24. Each contestant must furnish a hitching device with a hole at least 3" wide x 3.75" long. It must be bolted tightly or welded to the drawbar. Drawbars are to be parallel to the ground, with a minimum of 18 inches from the center of rear axle to the hook point, a maximum height of 20 inches to the top of the drawbar. Drawbars must be stationary in all directions. No Clevises Allowed.

25. Drawbars must be rigid in all directions with no movement allowed. Drawbars must have the pivot pin on the same plane as the hitch point and parallel to the ground within 1.5”, Plus or minus, per foot of length. This translates into a legally allowed 15 degrees or less of drawbar angle.

26. Diesel engines will only use VP Fuel Only. 

27. No fuel additives such as nitrous oxide will be allowed. 

28. Engine brand must match sheet metal brand and rear end brand, tractors must be equipped with stock appearing factory block or factory replacement form a kind model of tractor being pulled. 

29. All tractors must be equipped with individual working rear brakes.

30. No aluminum heads or recast heads will be allowed, only OEM heads. No 4 valve heads. No Deck Plates

31. A curved exhaust pipe is not allowed. All exhaust will discharge vertically. Two cross bolts 3/8 inch in diameter are to be used in the exhaust system of turbo tractors.

32. All tractors must retain stock wheelbase measured from the center of the rear axle to the center of front axle. 

33. Maximum tractor length for all tractors will be 13’ from the center of the rear axles to the furthest point forward (including weights). All tractors can have a 6 maximum tow loop that may exceed the 13' limit. 

34. No computers are allowed that controls any mechanical operation of the vehicle. 

35. All tractor classes with an RPM limit must purchase an RPM sending device and mount this device to the tractor. The connection/hookup to the remote unit for this device will be mounted at the rear of the tractor next to the ·air/ignition kill switch.

36. All tractors in classes with an RPM limit will have their RPM sending device connected to the remote tachometer as they pull the sled down the track when the remote tachometer is mounted on the sled.

37. A 1” diameter light will be placed in proximity to the hook point and sensor to aid in hooking the vehicle to the sled. 

38. All tractors must provide a clear view from the hitch straight up with a width of au, and this area must be free from obstructions. This means that no weights should be placed in an area 8” wide extending upward from the top of the drawbar. 

39. Maximum tire size will be 20.8x38, 18.4x42 o r24.5x32. Must be uncut, no shaving or grinding permitted. Radial tires are allowed. NO specialty pulling tires allowed. No Rear Aluminum Rims. 

40. Tractors may use aftermarket hitches. PTO and rockshaft housings may be removed. 

41. Maximum cubic inch will be 470.

42. Maximum rpm will be 3000 rpm. 

43. Any tractor running a stock bore and stock stroke motor up to 470 cubic inch will be allowed to compete at 2800 RPM’s. (To be re-evaluated after 6 hooks in 2021). 

44. The class is in charge of reading the RPM Box 

45. If the remote tachometer registers over 3000 rpm, the driver must be notified before leaving the track, and must pull to the end of the track out of the way and checked with the association hand tachometer one time. If the hand tachometer registers 3000 rpm or less, the hand tachometer will over rule the remote tachometer. General Disqualification rules apply. 

46. The hand tachometer will be used at the end of the track if the RPM box is not working properly. 

47. Tractors must run one of the turbo charger of following per tractor. Turbo must be either a Switzer 3LM-466 turbo with 2.41 exhaust housing in the out of the box form or the Switzer S300 2.36 inlet turbo. The S300 is limited to a 90 housing with part number 177272 or 100 housing with part number 177209. Turbos must be in the out of the x form with NO modifications. No billet of aftermarket wheels allowed. 

48. No intercoolers, intake air cooling devices or water injection components are prohibited.

49. No 4 valve heads allowed. 

50. VP fuel for diesel motors only. No pressurized fuel sources of any type (IE LP, NOS etc.) 

51. Homemade frontend are allowed, but must have skis as per diagram. 

52. One fuel injection pump for Diesel motors. Fuel pump limits will be NO larger than 13 mm. Can be either A-Pump or P-Pump. Other style pumps are allowed but no billet housings. 

53. Only OEM manifolds are allowed. A one inch spacer may be used for mounting purposes. 

54. No component tractors-must have tractor transmission and rear end. 

55. "shift-on-the-fly"(i.e. torque amplifiers, powershifts, over/under etc...) Shifting on the fly is still allowed. Up shifting during the pass is allowed, but NO downshifting is allowed. 

56. Gas engines can run carburetor of choice. 

57. Kill Switches must be Zip Tied. 

58. In case of sled malfunction in that distance cannot be obtained, participating tractors will evenly split prize money and points. 

59. Tractors caught not using current Spec Fuel and/or Water: 1st offence; No Points or Prize Money for the event that night and a $500 fine that must be paid before that Tractor can pull in that class or any other NK Class. 2nd Offence; Tractor cannot return for Two (2) years and One (1) day from date of 2nd offence and a $500 fine to be paid before the Tractor can pull in that class or any other NK Class

60. Must have Stock Frame Rails.