There are two main types of modern logging trucks: those used on uneven ground and trails in the forest where they were cut, and those used for transportation on normal highways and roads.[5] The suspension and tires of an off-road truck are particularly important, as roads in forests are bumpy and often temporary. Solid, low-pressure and high-pressure tires are used. Up to nine axles can be used to provide low ground pressure and good traction.
Timber is often grown on rough terrain that is unsuitable for farming, so the hill climbing ability of a logging truck is essential. The steepness depends on the quality of the surface - mud and snow are harder than gravel and soil. For a manageable slope, the speed will depend on the power of the truck.[7] Legal weight limits vary by jurisdiction, but range from 80,000 to 88,000 pounds (36,300 to 39,900 kg)—approximately 40 short tons (35.7 long tons; 36.3 tons) in the southern US states, for example.
One or more cranes or winches can be fitted to the truck to load the logs. Logs are usually unloaded by allowing them to roll over to the side.
