Deflation is often controversial, yet an important technique that should be practiced and implemented. Here are a few guidelines:
- Deflation improves traction but reduces ground clearance.
- Wheelspin with deflated tyres may cause the tyre to ‘debead’, that is to come off the rim. This may happen in rocky or sandy conditions.
- Tyres should be deflated when cold, not hot (hot air expands and gives higher tyre pressure readings). You could unseat a tyre from its rim when it cools down.
- In rough terrain, deflation also allows tyres to absorb more shock.
- In rocky terrain, deflated tyres can mould themselves to rocks as they go over them.
- Inflate tyres as soon as possible. Select your tyres according to the road conditions where most vehicle usage takes place.
It is important to consider these factors: size, width (this has an influence on flotation) and load/speed rating. Check wheel balance and alignment after protracted rough off-road travel.
Sand: Lower pressure to increase traction. It is worthwhile to deflate the front tyres only, as this will compress the sand for the back tyres to ride over. As hot sand has little moisture, it is looser and more difficult to drive on.
Keys to successful sand driving are momentum and tyre pressure. Deflate your tyres (45% of normal pressure is about the limit). Momentum and speed stop the vehicle from becoming mired in the sand, while dropping your tyre pressure creates a bigger tyre ‘footprint’, spreading the vehicle’s weight over a larger area and giving you more grip.
So drop your pressures when you are driving in hot sand or in gravel (it will give you a more comfortable ride), but remember that fast cornering on soft tyres is highly dangerous (you can roll the tyre off the rim), and don’t forget to re-inflate when you are back on hard ground.
* Never brake hard in soft sand. Your wheels will dig in and you’ll stop faster that you expect. Simply * decelerate, as the loss of momentum will halt the vehicle.
* Always stop on a downhill or on the flat.
* Avoid wheel-spin – the vehicle will simply dig down into the sand.
Rocky Terrain: Whilst deflation allows better grip, be careful not to spin or pinch a softer tyre as this could unseat the tyre or damage the sidewall.
Mud: Slightly lower pressure will increase the surface area and improve flotation, but beware of hidden obstacles.
Water: Do not lower pressure in water as obstacles under water may not be visible. It also lowers the vehicle’s clearance.