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Pick a compressor for your needs.

ipump4x4

Inflating is as important as deflating. When you are done driving in the dunes or in the bush, you have to get your tyres back to the correct pressure for driving on gravel or tar roads.
To do that frequently you need a quality compressor

Hard tyres for tar. If you constantly drive your tyres underinflated on hard surfaces, it will start to crack between the contact patch and sidewall.

Offroad tyres are designed to drive around half-inflated in sand and mud. A flatter tyre has a bigger surface area in contact with the ground and this gives better grip. And it doesn't puncture as easily on those sharp rocks.

But afterwards, if you drive 100km/h on a tar or gravel road, and your tyres is still at 0.9 bar, you are looking for trouble. A vehicle driving on flat tyres handles badly at speed. The tyres overheat and a sidewall could disintegrate.

Stress on a tyre will also cause it to crack, especially between the contact patch and the sidewall. This will cause the tyre to shred, perhaps at 120km/h on your way to see Stormers getting yet another hiding.

What should I consider when buying a compressor?

How often will I use it?

Weekend warrior. If you are in the dunes every second day(even if you were just sent out for a half loaf and coke), get the best quality compressor.

Occasional rider. If you drive a trail once every two months, the average Chinese compressors will work well and last well.

Once a year. If you go to the Richtersveld once a year you can buy the cheaper one, but make sure it won't fail on you.

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Yes, (pump) size matters.

If you want to fit the compressor in your vehicle, make sure it fits in the space available.

If you want to transport it loose, you have to remember that some compressors come in a hefty case. Some also have a tyre repair kit, extra valves, soapy water, lids an extra pressure meter and a deflater.

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So what does the compressor weigh?

These days every gram of weight on a 4x4 counts. Driving overweight is not only illegal, but dangerous too.

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Does it pull serious amps?

The pumps electrical wiring must be thick enough to handle the current it draws. Some draws up to 65Amps. If it is not thick enough, make sure that you can replace it.

It's also important that you don't have a drop in current.

There is a simple formula you can use to calculate at what amps a wire will start smoking: for every 10 amps a wire has to carry, it needs one square mm and for every meter length it needs another square mm, add these together, add another 20% and you'll be safe.

So a pump that draws 60A current through a wire of 3m will therefore need a wire of at least 11 square mm. But you do not get that thickness of wire, the next size up is 16 square mm. So you need to use that.

Always make sure that the engine is running when using your compressor.

Some important compressor tips:

Give me power. A compressor draws a relatively high amount of power off a battery and it is advisable to let the engine run while you pump, otherwise you might end up with a flat battery. You can even up the refs a little to make sure the alternator generates enough power. Always connect the compressor to the cranking battery so most of the power comes fro the alternator, otherwise you'll run down your extra battery.

Modification. The air pipes, especially the yellow spiral ones, that comes with the compressors, are so thin that they restrict the air flow. They also break easily. Rather buy a high-pressure air hose, with an inside diameter no less than 8mm. You can also get all the couplings and fittings from a compressor shop to make a professional air hose.

Use your own tyre pressure meter. An inline pressure meter in the pipe is impractical. A meter can't give you an accurate reading while air is flowing in the pipe (and many of the Chinese meters are very inaccurate in any event). In order to take an accurate reading you have to walk from the valve to the pump to switch it off, walk back to to the meter to take the reading, and then walk back to turn it back on again. Life should not be that hard, rather use your little handheld tyre pressure meter for a reading.

Should I have the compressor installed in the engine compartment of the  vehicle? I reckon this isn't the best choice. There is too much mud and dust and that is not good for the compressor, secondly it is too hot in there, that will damage the compressor and hot air is thinner than cold air so you will have inaccurate readings

Rather install it in the boot, or in the back of the bakkie or even behind the seat. The important thing is that the wiring must come from the main battery and that the right size wire is used.

Don't blow a fuse. Is there a fuse in the positive wire? Make sure the fuse is up to the task. The ordinary blade type is not recommended because it can heat up easily and melt. Rather use the strip type.

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