Off-road tyre pressure warning

Many caravan travellers could be hammering their vans into an early grave and costing themselves thousands of dollars in repairs and lost resale value by not lowering tyre pressures when they leave the bitumen.

This is the warning of a number of experienced manufacturers who believe that caravanners need to be educated about this most basic item.

“Most people run their tyres way too hard on unsealed roads,” complained Enzo Gnocato, the founder/builder of Van Cruiser caravans.

“I believe 70 per cent or more of all caravanners don’t drop their tyre pressures enough – or at all – in these conditions.

"They usually have no idea that they're giving their van such a hard time and when something fails they blame the manufacturer when a little care could have avoided the problem.

“You can have the most sophisticated suspension in the world, but if your tyres are rock hard you're going to give your shock absorbers such a hard time that they will soon overheat and be virtually useless and then your caravan and its contents will have to absorb all the shocks.

“Sometimes it’s not the obvious things that suffer. For example I’ve seen the plastic feet on microwave ovens hammered right into the base. You can build a caravan like a tank, but it will be too heavy for most people to tow.

“But your tyres are your front-line shock absorbers and if you lower their pressures, everything above them will get an easier ride and your investment will last longer.”

The problem facing the caravan industry, says Gnocato, is that there isn’t a single tyre pressure rule to follow to cover all road, suspension type, weight, loading and ambient temperature scenarios.

Opinions vary on ‘how much is enough’, to drop your tyre pressures, but there are some basic rules of thumb.

A starting point is to ‘read’ your tyres’ sidewall, where you’ll find their maximum cold inflation pressure – usually expressed in ‘psi’ – plus their maximum load rating.

These pressures relate to on-road travel, but if you leave the blacktop, different rules apply.

The tyre manufacturer can’t tell you exactly what pressure to run because there are so many variables, but as a very basic guideline, drop your pressures by at least 50 per cent.

On most caravans weighing around two tonnes or more, this will mean setting them at 25-30psi according to Gnocato.

“This is where common sense comes into it,” he says. “You can’t expect to travel at on-road speeds at these pressures because their sidewalls won’t be as stiff and your van will be less stable.

"But if you're on a gravel or corrugated road you shouldn’t be travelling at over 65-70km/h anyway.”

Some experienced off-road travellers suggest even lower pressures – down to as low as 20psi.

Trakmaster off-road caravans founder and experienced Outback tour guide Russell Seebach recommends these lower pressures to give your caravan the smoothest possible ride.

“If your tyres are relatively new you can drop them quite low without any damaging their radial belts,” he said.

“When a customer specifies our air suspension we even suggest they run their tyres at 35-40psi on road, depending on the caravan’s size and weight to give it the smoothest possible ride.”

I recently crossed Australia from the far West to East with two Bailey Rangefinder prototype on-road caravans fitted with basic leaf spring tandem suspension and we took advice from a very experienced Outback traveller at Laverton before embarking on 1100km of unsealed and corrugated roads to Uluru.

“Don’t worry about the numbers,” Mick told us. “Just drop the pressures until you see the tyre wall start to bag.”

We did and it corresponded to 20psi all round on these two-tonne caravans and we never had the slightest problem on nearly 2500km of unsealed roads we covered on the trip.

But Mick, like other experienced travellers, also had a warning.

“If you let your tyres ‘bag’ too much you will make the sidewalls vulnerable to rock damage and if its stinking hot you could also damage their structure, so you need to be very aware of the travelling conditions.”

What – use common sense? Now there’s a radical idea!