As we continue our Simpson Desert crossing series with the Haval H9 and Great Wall Stead, this week, we look at tyres; the most important part of your 4×4.

THE STORY SO FAR – we’ve decided to drive the Simpson in a week in an Haval H9 and a Great Wall Steed, as detailed in Part 1. And before we come back to the trip itself, we’ll be covering some of the preparation for a Simpson Desert crossing or, indeed, any off-road trip.

Any off-road camping trip involves an element of risk, and the preparation has to focus first and foremost on managing that risk. Then comes comfort and convience.

In the case of a Simpson crossing the overriding factor is the remoteness, the distance from the nearest source of assistance. In the middle, you’re about 250km worth of slow-going sand dunes and rough roads from either Mt Dare or Birdsville, and that would be a long day’s drive for most cars. Even then, neither location is exactly a major city in terms of medical facilities and the like. What we wanted to do was to not break down, not get stuck, and not have any injuries. And we wanted to be able to recover from all three if needs be. 

So let’s look at the risks and what we did to mitigate them, starting with tyres.

The single biggest reason modern vehicles are brought to a halt is a puncture. It is true that thanks to better tyre technology punctures are becoming more and more rare, and many young drivers have never had one. That’s also why we see more and more space-saver spares, or run-flats. That’s fine for city cars where roadside assist is just a phonecall away, but it’s outright dangerous for outback travel. So what we did to manage the puncture risk was:

Take new tyres – our cars had tyres with less than 10,000km on them. Newer tyres have deeper tread, and the deeper the tread the less the chance of a puncture. Some offroad tyres have tread about 15mm deep so if you rolled over a 15mm tack it wouldn’t even get to the carcass of the tyre, but on an old, worn road tyre that 15mm would see the tack go right through tyre and you’d have a puncture. And older tyres lack the suppleness of new ones.

TPMS – both the H9 and Steed had tyre pressure monitoring systems (TPMS), which are frankly brilliant and should be mandatory for all vehicles. These systems are very useful for checking pressures, but have a huge advantage because you can instantly tell when you have a puncture. In today’s cars it’s hard to tell when you have a puncture – the tyres are low profile so the car doesn’t lean much when it has a flat, and noise insulation is very good. It doesn’t take much running at no air pressure to ruin a tyre, so stopping immediately is critical, especially with a modern vehicle which is extremely heavy. Many tyres have been ruined not by the initial puncture, but by driving on it after a flat.

Low pressures – the lower the pressure, the less the chance of punctures. Yes, the sidewall bags out, but not by much and the puncture resistance of the softer tyre outweights any sidewall disadvantage. We reduced tyre pressures as soon as we hit the dirt, and progressively further as the going got slower.

That’s what we did to reduce the risk of tyre problems. Now we need to think about what we’d do if we did have a problem:

Full size spare and second spare – the spare tyre was for both cars brand new, and a full-size. We also took a second spare tyre to make a total of six, but only five wheels. We had the means to remove a tyre from a rim and refit it, and it was extremely unlikely we would damage even one wheel let alone two, so we saved the weight of a sixth wheel.

We had two sets of tyre levers and repair tools although between us the group of four cars and seven people owned probably six sets. Again, for critical tools bring two but there’s no point everyone loading up with the same tools. That space and capacity is better used for things like water.

Spare components – we had several spare valves and valvecaps, plus the means to replace them.

Tyre plugs – a nail or similar in the tread of a tyre is easy to repair, just insert a plug. Every vehicle had a supply of plugs.

Patches and wire – if we couldn’t plug a tyre then we had the tools to remove the tyre and patch it from the inside. And worst case, stitch the tyre together with fishing wire, then apply a patch.. That might be needed for sidewall gashes.

Air compressor – used for reinflating the tyre if it needed to be removed from the wheel, and potentially also for keeping up with slow leaks.

Experience -five of our group had long experience in tyre repair techniques, so none of us would be trying it for the first time out in the bush. This is really important. If you haven’t repaired a tyre, then go to your local tyre shop, buy a cheap rim and pick up a free old 4WD tyre. Take it home, and drive nails into it, slash it and repair it. Never try a skill for the first time for real. It can be quite good fun seeing just how badly damaged a tyre you can repair.

So with all that, it would take three unrepairable tyre failures per car to strand that car. That would be unlikely, and if it did happen then the backup plan was to send one of the other vehicles to go get more tyres. The stranded vehicle would be left with plenty of provisions for the wait. We carried a satellite phone so we could even order in the tyre and have it waiting for pickup, assuming Birdsville didn’t have any suitable ones in stock. All of the cars took commonly available sizes so availability would not have been a problem, and we would just need the correct diameter, width and rim size to get out of the desert, not exactly the same manufacturer and model. 

It would have been nice if the vehicles on the trip had been able to interchange tyres, but sadly that was not the case. If you do reguarly travel with the same group of vehicles do give some thought to running the same diameter tyres, on the same wheel size and close to the same width.

One thing we didn’t do that I advise everyone else to do is to replace the tyres with light-truck construction tyres as opposed to the lighter duty passenger construction tyres.  Not only are these tyres less likely to puncture, they’re easier to repair as they are tougher, particuarly in the sidewalls.

The reason for not replacing the tyres was that the rubber on both H9 and Steed wasn’t too bad; the Steed ran 16 inch wheels and the H9 17s, so not fragile low profile tyres and in the case of the H9 the standard tyres were Cooper Discoverers. The high profile meant we could air the tyres down and not be concerned with damage or punctures caused by the rim pinching the tyre, unlike say a standard fitment of a 19 inch wheel.  It is also far easier to remove a 17 inch tyre from the rim and fix it than a 19 or 20 inch, another reason I don’t like low-profile tyres.

So as this was to be a one-off trip, and I felt with the mitigations above the tyre risk was sufficiently well managed. You’ll see later on whether that turned out to be correct or not.