Tested: Trailhead tyre deflators

Tyre pressures are important if you travel off the bitumen with your car, camper or caravan – or they should be.

Too high on rocky roads and your teeth and everything on your rig will rattle and you’ll sink like a stone on sand; too low and your tyres will overheat on hard surfaces and their sidewalls eventually will fracture, leading to failure.

However, stopping for the 10-15 minutes or so it will take you to deflate the six or eight tyres on your camper/caravan rig is a chore and if you have kids on board, a hassle.

You can use keys, twigs or a ball point pen to press the valve core to release air, but you then need to stop the process periodically and consult a tyre pressure gauge to check if you’ve done enough. If you’ve let out too much air, then you’ll have to go through the whole process of re-inflating, checking, etc.

Even easier is to screw on an American-made and pre-set Trailhead tyre deflator onto each valve and allow them to drop your tyres to the desired pressure while you’re on a ferry, or even driving.

Distributed exclusively in Australia by 4WD specialists TJM, the small cylindrical valve extensions are factory-set at 12psi, but you can pre-select any pressure from 5-40 psi.

To start with, you use the supplied hex-head key to unscrew the Trailhead’s inner core out until it’s flush with its exterior housing, which is equivalent to a setting of 5psi.

You then use the hex-head key to wind the core back in, with each 360degree clockwise full revolution being equivalent to an increase of 1.5psi for the 5-20psi range and 3psi for the 15-40psi range.

If you're heading onto sand, which we did recently with two camper trailers in tow behind an Isuzu MU-X SUV and a D-Max crew cab ute, then you’ll probably pre-set them to about 18psi.

These pressures worked for us, but you might need to vary them up or down depending on your tow vehicle and the weight of what you are towing.

As a general guide, a 25-30 per cent decrease in tyre pressure will give you up to 250 per cent improvement in traction, by increasing the depth and width of the tyre on the surface, while lower pressures also allow your tyres to ride more easily over obstacles, like ruts and stones.

The great feature about the TrailHead deflators is that you don’t need to wait until the deflation process is finished, as they're designed to allow the vehicle to be driven at up to 30km/h while in operation.

Personally, I’d rather remove them before heading into thick sand, as they protrude from the valve and might easily be snagged.

In practice, if you have a tandem caravan in tow, the first deflator will probably have done its job by the time you complete a lap of your rig fitting them.

They cost around $100 per set of four, so you’ll need to outlay for two sets if you have a tandem off-road caravan.

Alternatively, invest in one set and adjust the pressures on your two-wheel camper or caravan manually while the deflators on the car are at work.

The TrailHeads come in a Velcro-sealed wallet with a simple manual tyre pressure gauge and a set of instructions.

There’s also a handy tyre inflation guide, which gives you a guide of what pressures to set for different gross vehicle weights (GVMs).

Strangely, this only covers common tyre sizes from 15-inch to 17-inch tyres, so it was useless for the 18-inch tyres fitted as standard to our two Isuzus and an increasing number of current SUVs and utes sold in Australia.

Plus, if you’re calculating the right pressure for your GVM, the calculator only gives you weight in pounds (which we haven’t used in Australia since metrication in 1972) , so you’re going to need to divide by 2.21 to check in kilograms.