When it comes to equipping your 4×4 with extras, it is often difficult to control yourself. You buy too much stuff so that when you venture off road, the problem isn’t what to take but what to leave behind! But one absolute essential is a compressor for the tyres.
Tyres are among the most important items on a vehicle. And when you are driving your 4×4, tyre pressures need to be adjusted for different types of terrain.
When you venture into the desert, for example, tyre pressures are normally let down to 0,8 bar. But don’t forget that when you leave the sand and go onto a rough gravel road, the sidewalls of the tyres will be damaged if you don’t inflate the tyres to their previous level.
This is why you should always carry a 12 volt tyre compressor. The pumps vary in size and shape, and also in price. A good 12 volt tyre pump costs around R1000.
Look after this little machine to ensure that you don’t get stuck in the bundu. Some people simply carry the pump loose in their vehicle. Others mount it under the bonnet. This is not a good idea. Mounting the pump in the engine bay exposes it to the constant high heat, and it is not designed to withstand these conditions. When you start pumping, it doesn’t take long for the pump to overheat.
Another problem with mounting the pump under the bonnet is that it gets soaked every time the engine gets washed, and the pump is not waterproof. In the long run, a pump mounted in the engine bay is going to act up, so rather carry it in the vehicle’s cabin.
Remember that if the pump is placed on the ground, the vibrations will kick up dust very close to the air inlet of the pump. Soon the filter will get blocked, or dust will even get into the pump. If this happens, it won’t take long for the rings to wear out. Believe me, I have learned this lesson the expensive way! So always put a floor mat under the compressor, and it will last much longer.
What works best for me is to let the pump stand in front of the radiator when the bonnet is open. Unfortunately, all vehicles do not have enough space for a pump to stand there, so another plan must be made.
On our recent trip to the Skeleton Coast, I used my 12 volt tyre pump to inflate the tyres when we went onto the hard gravel roads. The pump was standing on the front of the open engine compartment and the flexible hose was long enough to reach all the wheels, although it had to be stretched quite a bit to reach the rear wheels. And, in the process, it pulled the tyre valve to one side.
When we drove off, we had travelled only about 5km before I had a puncture in a rear tyre. We could not find the leak in the tyre, but when we pumped it up again I heard a leak at the valve, just where it entered the rim. The stretched hose had pulled the valve to one side, causing it to crack. It was quite a big job to replace the entire valve, but in the process I learned not to allow the valve to be bent when pumping the tyre.
Pumping hot tyres can be a big problem. Tyre pressures should be checked when the tyres are cold. Heat increases the volume of the air and subsequently raises the tyre pressure. Obviously, the pressure in the tyres will drop when they cool down. The recommended pressures are for cold tyres, so you need to keep this in mind when inflating warm tyres.
When a tyre is at the correct pressure, there is less flex in the casing and the rolling resistance is also less. This will cause less friction, with the result that the tyre will stay cooler and the fuel consumption of the vehicle will be reduced. The wear on the tread will also be more even.