Johann ‘Tyres’ Viljoen tells us about tyre width vs tyre profile, and how to achieve an optimum tread footprint off-road
When fitting an off-road tyre, it’s important to remember that fitting a wide tyre with a low profile on large rims will not benefit your vehicle off road. It’s much better to have a tyre with a tall profile on smaller rims with a narrower width section.
Narrow and tall tyres allow you to deflate more in off-road situations like sand or mud, which lengthens your footprint to improve braking, traction and stability.
Very wide, low-profile tyres are easier to de-bead at low pressures, but are extremely difficult to put back on the bead of the wheel. They also increase rolling resistance.
Drastically increasing the tyre size will require either an increase in power from the engine, or a shorter diff ratio to compensate for the bigger circumference of the tyre.
Lastly, it is important to remember that for a specific off-road terrain you would NOT use the same tyre pressures on a three-ply sidewall Light Truck (LT) tyre as you would on a two-ply or SUV tyre. For example, a Cooper Discoverer S/T Maxx or A/T3 LT (both all-terrains) or BF Goodrich KO2 LT (all-terrain) will require about 30-40% more deflation to achieve the same footprint as a two-ply tyre like a Bridgestone D694 or General Grabber AT3 all-terrain.
Johann Viljoen owns the well-known 1st Alignment Centre and Ironman 4×4 dealer 1st Outdoor and 4×4 in Stikland, Cape Town. He is a fundi on all things relating to tyres, 4×4 accessories and the outdoors.
