Tyres for BIG wheels

As 4x4s become more performance-oriented, thanks mainly to high output supercharged petrol and turbo-diesel engines – and towing capacities increase, it’s inevitable that brakes need to be larger.

Bigger brakes are also beneficial for increasing the effectiveness of traction and stability control systems.

In the ’80s most recreational wagons ran on 15” rubber and working wagons and utes ran split-rim 16” ‘skinnies’. Increasing brake sizes meant the 16” became the industry standard. By the ’90s larger brake packages led to the 17” tyre making its mark. In the late ’90s, 18” and 19” became standard on high-performance machines.

In the markets where these vehicles are born and for most export markets, the requirement is for high-speed capability, which means relatively lightweight tyres with shallow tread depth. In Australia the tyre demands are different: We require less high-speed ability, but much greater puncture resistance, which decrees a heavier-built tyre with deep tread. We are a tiny market in global terms, so we’re used to waiting for manufacturers to develop the appropriate rubber.

With the 19” tyre we struck pay dirt, because Land Rover needed tyres for its global G4 Challenge competitions. Goodyear developed the Wrangler MTR 255/55R19 tyre to suit the Discovery 3 and the Rangie Sport. In recent months we’ve seen other large-diameter tyres hit the market; notably Cooper’s LTZ for 19- and 20-inchers.

We’ve tested the 19” MTR extensively. On a loaded Rangie Sport diesel we ran it through salt lake mud in South Australia, up and west to the Kimberley. Pressures were a constant 30psi and the MTRs never looked like getting a puncture.