Call Us:
With knowledge of your chosen tyre and its design characteristics, you can adjust your tyre pressure to suit the terrain and vehicle load without compromising safety.
Adjusting your tyre pressure can be a hit and miss operation. Using the 4psi method is a good place to start when determining correct inflation pressures.
The 4psi rule.
- Start your test with the vehicle loaded as it would be for touring.
- Initially use a nominal tyre pressure to begin. Say 40psi.
- Drive at highway speed for minimum 30mins to let the tyres heat up.
- Stop and check your tyre pressures.
- Pressure increase of 4 psi is deemed correct.
- Pressure increases above 4psi....your starting pressure is too low.
- Pressure increases below 4psi....your starting pressure is too high.
Note: Record ambient temperature during the test, as this will affect the outcome.
How does correct pressure help tyres survive heavy loads and extreme heat?
Radial tyres dissipate heat through contact with the road surface. As a tyre rotates, with constant load and torque passing through the carcass, contact with the road makes the sidewall continually flex. This flex causes friction and heat within the tyre (additionally, brake heat permeates through the wheel to the tyre carcass). The heat transfers into the tread via the sidewalls. The Tyre and wheel as a unit reaches and exceeds the temperature of the road surface. Rotational contact with the road surface via the tread acts like a heat sink and stabilizes the condition. The temperature within the tyre becomes constant.
In the worst case, if your inflation pressure is way too low (or you have a slow leak) the sidewall will be flexing to a point where the heat generated will overwhelm the tyres ability to transfer the heat. As a result, the tyre will fail, and delamination will be inevitable.
Note: Aggressive mud tyres have difficulty dispersing heat because they have a low rubber to void ratio, therefore mud tyres will wear faster. Highway tread patterns have high rubber to void ratios and are capable of dissipating heat more rapidly therefore lasting longer with less tread wear.
What pressure do I use for off road driving?
Reducing tyre pressure for off road driving is an effective way of gaining traction and increasing ride comfort. Careful attention to tyre pressure can make short work of sand, mud and snow.
There is no absolute correct tyre pressure for off road use. There a just too many variables to make a general rule. Such things as sharp stones, tree roots, ruts and sticks can easily damage a tyre if the pressure is too low. Conversely, loss of traction because of firm pressures can harm the tyres through spinning on similar rocks and tree roots.
As a starting point, drop 1/4 off normal road pressures, then adjust to suit the conditions. Be careful not to go below 20psi without some form of beadlock. Reduce your speed when using low pressures. Braking and cornering can be awkward or hazardous at low tyre pressure.
