Open Modified tractors are those using any combination of Automotive, Marine, Aircraft or Turbine engine(s), transmission(s) and final drive. There is no limit to the capacity. Blowers and Turbo-charging is permitted. Open Modified tractors are permitted the use of Engine Management Systems.

Weight classes are:

4000 kg
4000 kg
4000 kg, excluding driver

No portion of an open modified tractor may exceed 14 feet forward of the centre of the rear wheel, including removable ballast. Maximum width of tractor is to be 8 feet at its widest point including ballast. Legal fuels are Alcohol including methanol, Water, Aviation Gas, Diesel, Kerosene, ULP, Nitrous Oxide and Premium Unleaded. A maximum of 20% Nitro Methane is allowed as fuel additive.