Last month, we talked about how a number of all-terrains are masquerading as off-road tyres, when in fact their carcass construction is no different to that of a road-biased tyre. However, it’s not that tyre manufacturers are ‘pulling a fast one’; it’s simply a case of tyre selection versus application. Most (non-practicing) 4×4 owners don’t need, or want, a heavy-duty tyre.
The Cooper Discoverer AT3 is a case in point; this tyre is available in both SUV and LT form. Take a 265/65/17 for example: the SUV tyre (designed for non-enthusiasts) weighs 17 kg, while the LT (designed for avid enthusiasts and heavily-loaded vehicles) weighs 20.9 kg. The LT is 23% heavier and far stronger than the SUV tyre, but aside from their weight differences, both tyres look identical in terms of tread design. If it weren’t for the letters ‘LT’ on the sidewall, you could hardly tell them apart. So if you find all-terrains going for a bargain price, ask the question: ‘Is it an LT?’
This brings us to another topic: BALANCE. Bigger, heavier tyres are often trickier to balance due to their rubber bulk. What’s more, they tend to cause greater vibrations when out of sync.
It’s a common problem. The consumer buys four LT tyres. The dealer fits the tyres. The consumer complains of vibration. The dealer rebalances the tyres. The consumer still complains of vibration. The baffled dealer blames the tyre manufacturer. The tyre manufacture blames the dealer. The consumer, caught in the middle, ultimately regrets his purchase.
So, what exactly IS the problem?
Well, all things are NOT equal, and that includes tyre-balancing machines − most of these are unable to apply load to the tyre, so they don’t replicate real-life conditions. What’s more, a number of older machines base their balancing calculations on a pre-calibrated setting which could be set on a much smaller rim and tyre size − say, a 13-inch.
Give this a try: Have your tyres balanced at Dealer A, then drive down the road to Dealer B and have them balanced again. Don’t be surprised if all four tyres are running out again. Why? Because your LT tyres weren’t balanced properly the first time, or possibly the second, third, or fourth….
In many cases, you can have your tyres “balanced”, removed from the machine, put back on the very same machine straight away, and the tyre will be running out, again! Don’t believe me? Test this theory yourself, or simply look for the rim that’s totally covered with lead weights, showing that the fitter couldn’t make up for the machine’s inconsistencies.
So, what now? Thin, lightweight tyres are usually easier to balance, so one option is to downgrade your LT tyres to a light-duty all-terrain that punctures at the sight of a bread stick. But, if you’d rather forgo the punctures, you can always look for a Hunter Road Force.
American-made, the Hunter Road Force costs tyre dealers about R360 000 for the machine alone, which is why you’ll find only three in the Western Cape. (Gauteng has more).
As far as I know, the Road Force is the only (patented) tyre-balancing machine that can apply load for a real-life test. It balances all four tyres while recording their respective discrepancies, then suggests a preferred order in which the tyres should be fitted: left rear, right rear, left front and right front. The accuracy of the machine is (laser) pin-point; it’s also able to check if your rims are untrue. Another trick is to take a particularly fussy tyre and to mount it at the rear left-hand side of the vehicle – as far from the steering system as possible.
If, by some chance, the Road Force can’t hunt down your tyre-balancing issues, then the problem could be related to tyre wear, tyre damage, or how your tyre is seated (beaded) on the rim. In this case, the solution could be a bead massage, but that’s a whole new story.
By Grant Spolander. Originally published on Cooper Tyres website.
For more information on the Hunter Road Force, and where to find your nearest machine, give Leaderquip Auto Services a call on 083 600 1603.
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