4WD MODIFICATIONS - TYRES & WHEELS
Run-flat tyres and emergency spare tyres have no place in the Australian market, especially for people who want use their 4WDs for trips more than 100km away from service back-up.
We were testing a Porsche Cayenne 4WD on graded forest tracks just out of Lithgow, NSW, when one of its expensive tyres went ‘pop’. No problem, we thought, we’ll just fit the spare and head back to Sydney, where it can be repaired.
We lifted the tailgate and the spare-wheel-well lid and to our horror we were greeted, not by a shiny spare wheel and tyre, but by a Bose woofer, neatly shaped to fit the well space!
Instead of a spare wheel there was a pressurised can of leak sealant that we were supposed to inject into the flat tyre, to seal the hole and re-inflate it. Given that the tear in the tyre was big enough to fit your hand into, it was absolutely certain the leak sealant wasn’t going to work.
Without backup vehicles we’d have been in a right pickle – no mobile phone coverage, nightfall imminent and about two hours’ walk into Lithgow. We’d have had to stay in town overnight and accompany a tilt-tray out to the stranded Porsche next day.
As it turned out, we had a VW Touareg with us and that vehicle shared its platform and wheel ends with the Porsche, so we confidently lifted the tailgate, in pursuit of its spare wheel. Residing under the spare-wheel-well lid was a skinny temporary spare wheel and a tyre that looked like it would suit a lightweight motorcycle.
Oh well, nothing else for it: we fitted the temporary spare to the Porsche and aimed out of the forest.
The temporary spare felt like it was made of solid rubber and the Cayenne’s traction control worked overtime on the loose gravel tracks as we tip-toed towards the bitumen.
We couldn’t go any quicker than around 10km/h or our teeth started to chatter. We reached the bitumen and crept back to Sydney, averaging around 60km/h and risking a rear-end shunt all the way.
At the end of this 130km drive the temporary spare was totally stuffed – and so were we.
Imagine if this happened in the Outback – hundreds of kilometres of gravel road away from tyre service .
After this experience we resolved never to test or recommend a vehicle with a temporary spare, which is one reason why you won’t see all brands of SUVs evaluated on this website.
Run-flat tyres are in the same category. To save the boot space taken up by a spare tyre the vehicle maker fits road tyres that have an inner supporting structure. In the event of a puncture the vehicle can be driven a limited distance at reduced speed, to a service outlet, where the tyre may be repairable, in theory, but in practice never is.
How dangerously stupid an idea is that? If the run-flat gives up because you need to drive 400km to the nearest service place – a not unreasonable distance anywhere in rural Australia – you’re stuffed. Even if you get there, what will you do for a replacement? You’ll have at least a three-day wait while the vehicle maker finds and air-freights a new wheel and tyre to you. The cost will make your head spin – budget at least a grand for the exercise, plus the cost of a motel.
A bloke we know was driving his brand-new BMW SUV on the Hume Highway – not exactly a bush back road – and told us his sad tale:
“The trip down was uneventful, as the BMW behaved beautifully: brilliant performance, heaps of power, frugal appetite; a pleasure to drive.
“I don’t think I have ever driven a car that steered so precisely.
“However, on the return trip, after Gundagai, a warning light came on, indicating a deflating tyre and the BMW has ‘run flat’ tyres, so there isn’t a spare, a jack, or wheel brace!
“On checking the handbook we were advised that we could continue driving on the flattish tyre for up to 150km, if we kept below 80km/h.
“The tyre looked okay, if a bit saggy, but the stiffened sidewalls were doing their job as we continued for the next 10 kilometres, keeping the speed below 70km/h, but all of a sudden the tyre shredded completely.
“We rang the NRMA and after an hour or so we were towed back into Jugiong, while our friends rang ahead for their son to drive over to retrieve us, as the Beemer wasn’t going anywhere in a hurry.
“There was no spare available (or any likelihood of there being one at Jugiong) so we went back to Canberra to buy a new wheel and tyre and reunited with the car later in the week – another 140km trip each way.
“This run-flat technology may work in Europe, but with Australia’s distances between places, it proved a liability,”
Consider these experiences before you buy any softroader – especially a European one. Check that it comes with a full-sized spare wheel and tyre that exactly matches the four on the road. If it doesn’t – don’t buy it.
Of course, it’s possible to buy a full-sized spare wheel and tyre for any softroader and bolt it into the cargo area, but you have the problem of ensuring that the securing fasteners are adequate. You’ll also lose a considerable amount of cargo space.