Truck axle configuration

Commercial vehicles are described by a two-number code such as 6x4. The first number counts wheel positions, two per axle, with a pair of twin tyres counted as one position. The second number counts how many of those positions are driven. So a 6x4 has three axles (six positions) and four driven positions, meaning two driven rear axles.

• 4x2: two axles, one steering at the front and one driven at the rear. This is the Tata Ace, the 407, most LCVs and intermediate trucks, and most tractor units for ordinary trailers.
• 6x2: three axles, only one driven. The third axle is a load-carrying lift axle that is raised when the truck runs empty to save tyres and fuel. Common on 25-tonne haulage trucks.
• 6x4: three axles with a tandem pair of driven rear axles. The extra traction suits tippers in mines and construction, and heavy tractor units pulling 40 tonnes and more, such as the BharatBenz 2826C.
• 8x2: four axles, twin steering axles at the front, one driven and one lift axle at the rear. The typical 35-tonne multi-axle haulage truck.
• 8x4: four axles with twin steer and a driven tandem, for heavy tippers and construction trucks such as the Tata Prima 3530.K.
• 4x4 and 10x4 follow the same rule: all four positions driven on an off-road LCV, or five axles with a driven tandem on the heaviest rigid trucks.

Driven axles are heavier and cost more to buy and to run, so operators choose the fewest that will give the traction and legal axle loads the job needs. The configuration also decides how much the truck may legally carry, because each axle has a maximum permitted load.