Maximum width of 6 ft. Maximum length of 8 ft. from the center of rear axle to furthest most point-Forward weights included. All power to be transmitted through the rear wheels. No four wheel drives, dual tires, chains or studs. Maximum tire size 18.4" x 16.1" Working brakes on the driveline or on rear wheels are mandatory. Shielding: Driveline brake components, if used, must be shielded 360 degrees with 5/16" steel or 3/8" aluminum. All driveline components must be shielded 360 degrees with 5/16" steel or 3/8" aluminium. Shielding shall be securely fastened. Engines must have side shields-minimum .060" thick, steel or aluminum. Shielding to be entire length of block from 2" below crankshaft to the head/block mating point. Chassis must have wide front axles with front wheels tracking within rear wheels. Front skid bars/pads recommended. Vehicle must have a fender between the driver and the tires that consists of a solid barrier. The fender must be a minimum of 1" over the height of the tires and must extend 4" horizontally from the inside edge of the tire in the same configuration as the tire. Minimum length of 18" at the top of the fender. Drawbar: drawbar to be constructed of 3/4 inch solid steel-or hollow tubing with minimum of 1/4" wall and a 5/16" steel safety cable. Drawbar must be regid in all directions. Point of hook to be a maximum 13" high from the ground and must be horizontal-Not vertical. Point of hook to be a minimum of 6 inches from the center of rear axle. Drawbar must have a 2" minimum round hole. Stabilizer Bars: Stabilizer bars must have pads where they meet the ground. Pads to be a minimum of 4" square, wheels to be a minimum of 5" diameter by 2" wide. Pads to be a minimum of one-half the tire diameter rearward from the rear axle centerline Pads to be a maximum of 6" above the ground. One pad to be on each side of vehicle. Drawbars and stabilizer bars must not be connected. Each stabilizer bar must be able to support weight of vehicle. Vertical bumper bars that extend rearward a minimum of 2" behind the rear most part of the tires are required. Front skid bars are mandatory on all tractors. Weights must not extend rearward beyond rear most part of tires. Vehicle must be equipped with a properly secured factory-type seat, or fabricated equivalent. Tractor must have a deadman throttle of positive mechanical type, with two return springs. Throttle must move forward/down to open and rearward/up to close the throttle. All foot throttles must have a toe strap. Vehicle is required to have a kill switch that interrupts the ignition and electric fuel pump circuits. Kill switch to be located 18 inches above the point of hook and within 6 inches of center in any direction. Kill switch must have solid steel or aluminum ring of a minimum 2" diameter and 1/8 inch cross section thickness. All tractors will be required to have a rear mounted back-up light activated automatically when the transmission is in reverse. The light must be a minimum of 2 inches in diameter and be white in color. Lamp to be mounted near the kill switch and be clearly visible to the hook person.
2.Clutches, Flywheels, Transmissions
Vehicles equipped with any type of clutch must: Use of blowproof bellhousing having no non-factory holes. Exception: Bellhousing may have a clutch maintenance of inspection hole and one 1" cooling hole. Be equipped with a block saver plate of 3/16" steel or 1/4" aluminum. Use only steel or aluminum conponents. No cast iron components permitted. Components defined as flywheel, pressure plate, floaters, and clutch discs. Automotive transmissions must have a securely fastened SEMA or equivalent approved safety blanket or safety shield covering the transmission and torque converter. Any flex plate used must be SFI approved. Vehicle must have positive reverse gear lockout and neutral safety switch. The switch must prevent the engine from starting in gear. Vehicle must have an operating reverse gear.
Induction must be naturally aspirated-No superchargers or turbo chargers allowed. Vehicle allowed one engine with maximum of eight cylinders, and two valves and one spark plug per cylinder. Maximum displacement of 500 cubic inches Any engine 415 cubic inch or less may use mechanical fuel injection or one single carburetor. Any engine over 415 cubic inches must use one single carburetor. Engine blocks may be aluminum or cast iron. Bore spacing on all blocks must be factory stock as intended by the OE manufacturer. Sheet metal intake manifolds are prohibited on all engines. Only passive data acquisition devices are permitted (data recorder) Aluminum heads are permitted. Harmonic balancers: Steel harmonic balancers are recommended. Factory OEM type units, if used, must be shielded with 5/16" steel 360 degrees and have a cross strap a minimum of 1" wide. This strap must be made from 1/8" steel or 1/4" aluminum and securely fastened. SFI approved balancers or hubs of steel do not require shielding. A bolt is required in the end of the crankshaft to hold the balancer or hub. All exhaust systems must discharge vertically or within 10 degrees in any direction of being plumb. The height shall be a minimum of 12" above the bend in the pipe. Only electric engine cooling fans are allowed.
Legal fuels are gasoline, diesel fuel, water, alcohol, and propane. All forms of nitro-methane, including nitrous-oxide and proypylene oxide are not permitted.
Protective safety equipment
Driver must wear a helmet and fire suit in good condition. Vehicle must have a minimum of two hoops of aluminum or steel rollover bars over the driver that are securely fastened to the frame and must be able to support the weight of the entire vehicle. Vehicle must be equipped with an automotive style lap belt seatbelt. SFI 5 point harness is recommended. Vehicle must be equipped with a fuel shutoff. Vehicle must be equipped with an operational fire extinguisher.