Tips on tyre selection
Choosing tyres these days has in some way become more difficult because there are so many brands and models to choose from, and because not every respectable brand makes a respectable multi-terrain tyre. Andrew St Pierre White shares his experiences
Large black round things that cannot be made attractive are not much fun to purchase. Unless you are a motor-head, it’s a bit like insurance: a major grudge purchase.
This is the challenge faced by tyre marketers when conceiving campaigns. Way back in 1982 I edited a General Tyre TV commercial and was loaned a Corolla to record sound effects. The commercial was filmed on gravel, so off I went, doing hand-brake turns and screaming around Honeydew’s gravel roads. Then I pulled the handbrake a bit too hard and the tyre came off the rim. At this point the fun stopped.
Last week, 27 years later, I shot a video about a 1400hp Lamborghini Gallardo owned by the owner of Dastek Engineering, and used as test-bed by the people who make the Uni-Chip. Watching it do doughnuts on a skidpan, throwing up clouds of smoke from its four spinning wheels, was a shoot to remember. Just four minutes of this and the tyres were cooked…
The point of these stories is that these two mornings’ work constituted about as much fun anyone can have with a set of tyres. Today I regard tyres as the one thing that is most likely to let me down on an overland trip. This is not to suggest I dwell on it, but I reckon that with most overlanders, eight out of ten mechanical troubles had on trips will have something to do with tyres.
At the risk of offending, here are my findings, and I think most experienced overlanders will agree or find similar experiences as these.
Satisfactory tyres for light SUVs that aren’t going to be doing any particularly challenging overland trips, are made by brands like Michelin, Continental, Goodyear, Pirelli and so on.
While many are called “all-terrain”, this is a marketing ploy. Many are not, and cannot withstand the rigors of gravel roads, high temperatures and high loads.
But, true overlanders with laden vehicles are not so fortunate and must choose more wisely. Alas, there are just four brands that make tyres that can be classed as true overlanders’ tyres. These are Cooper, BF Goodrich, Bridgestone and Goodyear.
If there are others, they are lesser-known brands and probably not easily available.
Which it the best?
There is no simple answer. Cooper’s mud terrains are immensely strong, both in sidewall and tread. But they are noisy. Cooper’s All-Terrains are good but not as strong as the others.
BF Goodrich: A huge favourite because they are strong, resist punctures, offer good grip and can take a beating. Mileage is good too. BF’s mud-terrains are equal to the best of Cooper but some say not as strong. In my book, BF All-Terrains and mud tyres should not be deflated to below 0,8 bar as anything below this causes them to slip off the rim very easily.
Bridgestone: I think the all-terrains are brilliant, but because of an unnerving experience last year in the Kalahari, which the manufacturer did not wish to help me solve, there remains a question as to their robustness. They do have remarkable grip in most terrains and don’t puncture easily.
Goodyear: Mud-terrains and all-terrains are both strong with good performance, but not as strong or puncture-resistant as Cooper and BF.
These conclusions are simplistic, I know, but for what they are worth, I reckon they may assist readers in making the right choice. Right now I have a set of new BF Goodrich 275/75R16 ATs on my Cruiser 100 and am off to the Kaokoland in August to do shoots for my TV show. I reckon Kaokoland is a good test for any tyre.
There is an overused maxim when it comes to buying property: Location, location, location. There is a similar one when it comes to protecting tyres from damage: Pressure, pressure, pressure.
Pressure is everything when it comes to the life of a tyre, and as a direct result ultimately plays a significant part in the safety of operating a 4×4. This is one subject were my opinions have changed over the years, and with experience comes more insight. There are few subjects in the world of 4x4s that are under such constant debate.
Reducing tyre pressures:
* When traction is marginal, such as on steep, undulating climbs or tricky, lumpy descents, shallow slippery mud and general off-road driving, tyre pressures should be reduced by about 20% of normal operating pressures.
* To reduce the shock effect of tyre impact when driving over rocks, pressures should be reduced by ?20%.
* To improve comfort, safety and stability on corrugations, pressures should be dropped by 15%-20%. Be careful of dropping pressures too low when carrying a load, because low pressures can also result in reduced directional stability and while making things more comfortable, reduced pressures may also cause handling difficulties.
* Likewise, excessively high pressures, set because of a heavy load or trailer, can also adversely affect handling, especially noticeable on gravel corrugations.
* If conditions require protection, such as on sharp rocks and in conditions where the tyre sidewalls are threatened, then I recommend dropping the pressures by as much as 30%. The trouble is, the lower the pressures the wider the sidewall will bulge, thereby making it more vulnerable. But like a balloon, which is easier to pop when fully inflated than when soft, a hard tyre is more vulnerable to damage by rocks than a soft one.
* If conditions require flotation, tyres should be deflated. On sand tracks where speeds are 40-50 km/h, drop pressures by 20%.
* On sand that is extremely soft, tyre pressures can be dropped to as low as 0,5-bar. However, at this pressure the risk of a tyre coming off the rim is high. Steer cautiously and drive slowly. Some tyres will not permit such a low pressure, as the bead design will not keep the tyre on the rim. In this case 0,8-bar is about as low as one can go. Tubed tyres can be safely reduced to 0,3-bar.
* A vehicle with tubed tyres can be driven more aggressively because the tube serves to hold the tyre onto the rim. If the bead is broken, there will be no loss of air. For this reason pressures can be dropped lower than with tubeless tyres. However, with such low pressures, sand and grass may find their way between the tyre and tube and cause punctures.
* At any pressure lower than normal, speeds must be kept down to prevent tyre damage, especially if you are using tubed tyres. Excessive speed on reduced pressures, with tubed tyres, will quickly wreck the tube and a blowout is likely.
Automatic tyre deflators
Solutions to the dilemma of how to let tyres down quickly have plagued mankind for oh, at least 25 years. Tools range from the long fingernail, a twig or matchstick, the tip of a Leatherman and, recently, auto deflators like the Staun, which is the best of them. Screw them onto the valve of each tyre and they deflate each to a preset pressure.
But I have found something I like even more: The ARB tyre deflator. Very fast, very convenient and very safe: there is no guesswork that each tyre is at the desired pressure. The best solution yet.
Whatever problem one has with tyres, it will have to do with pressure or temperature. Surely if a driver can monitor them, then any upcoming problem will be made known, because there will almost always be warning signs well before the problem actually strikes.
One of the very best tyre monitoring devices is the Tyre Dog. A simple panel receives signals from transmitters attached to each valve. Every few seconds it reads pressure and temperature and audibly warns of trouble ahead. The next best solution yet. I know for a fact that had I had one of these fitted, my Kalahari trip last year would not have been aborted.