Motoring

Alan Judd

I once met a man who worked for what was then called the Government Efficiency Unit. He reckoned that talking about his job was the quickest way to empty a room.

I’ve found the same with talking about tyres. If I’m at a drinks party and feel I just want to sip and watch for a while, I merely mention tyres as my principal interest and an instant cordon sanitaire opens up around me. Except that I do know one respectable married lady who finds chunky tyres so irresistible that she bought herself a small tractor. She hardly ever drove it but kept it in the barn and would slip out and stroke its big rears whenever the mood came upon her.

Tyres have been on my mind recently for a more mundane reason – replacing the fronts on my Volvo. They weren’t quite at their minimum, which for cars is 1.6mm of tread wear across 75% of tyre width. You can gauge this by tread wear indicators – little raised bits within the channels signifying that the tyre needs replacing when the tread wears down to them. You can also get a rough idea by putting a 20p coin in the channel. The 20p rim is 2mm; so, if the channel depth only just covers that, you’re still legal but near the limit.

Tyre size for the Volvo is 225/50/17. This translates as follows: 225 is the cross-section width of the tyre in millimetres; 50 is the height of the tyre expressed as a percentage of the section width; 16 is the diameter of the wheel in inches. You can fit different sizes of tyre as long as they have the same wheel diameter. Other symbols on the tyre wall variously indicate maximum speed, pressure, load, temperature rating and the number of plies. The letter R means radial, applying to almost all modern tyres in which the reinforcing plies run at right angles to the direction of travel, from tyre lip to lip. Older tyres were cross-ply and measured differently.

Anyone still awake at this point should resist the blandishments of car salesmen who praise cars for their large alloy wheels and low profile tyres, ie tyres with a low height-width ratio percentage figure. They derive from racing where they were found to save seconds on cornering because there’s less rubber flexing between road and wheel rim. They are inexplicably fashionable, even on large 4x4s, greatly to the benefit of tyre-makers because they’re more expensive, wear out more quickly and damage more easily. But they’re irrelevant to the overwhelming majority of drivers who are not seeking to shave points of seconds on corners and who appreciate the smoother ride offered by having more rubber between them and our pot-holed roads.

Recommended Continental tyres for the Volvo cost £130 each, fitted. I could have found cheaper, all the way down to budget tyres for £75 and part-worn for £35. But a main dealer I knew experimented with budget tyres and found the cost reduction roughly matched by reductions in tyre life; so there’s no real saving unless you’re selling the car. The tyres I replaced lasted about 23,000 miles. I’ve had better – 37,000 on Michelins on a Discovery – and worse – 12,000 on front low profiles on an Audi.

There are all sorts of ways to save money on motoring maintenance but, where tyres are concerned, it’s best to play safe. After all, those few squares inches where your rubber meets the road are all that keep you on it. There’s more to be said about tyres – lots – but, thanks, I’ll just finish my drink and go.