Asked a question I couldn’t answer about tyres, my first thought was to turn to the late L J K Setright (1931-2005), who died 20 years ago this year.
Then doyen of motoring correspondents, he was a tall, rabbinical, bearded patrician, provocatively pedantic, engagingly discursive, courteous and eccentric.
Who else could tell you that the speed of a raindrop unaided by wind is 18mph? Or that there were more deaths on British roads in the first two years of the Second World War than in the armed forces? (The blackout was largely responsible.)
He proudly held the record for appearances in Private Eye’s Pseuds Corner. When asked by an editor to tone down his style, he submitted his next column in Latin.
He became known as the Wittgenstein of the motoring press, closer, according to design guru Stephen Bayley, to Isaiah Berlin than to Jeremy Clarkson. But, like Clarkson, he knew his cars. His favourites were sporting Mercedes and, at the launch of an SLK, I almost met him.
With his fedora and chain-smoked Sobranies, the scholarly figure stood out among the motoring hacks and I was determined to nobble him on return from our track circuits. But he loved speed and was so much faster than me that by the time I clambered out, he’d finished and gone home.
Bristols were one of his obsessions – among his two dozen books was an expensive illustrated history published by the Palawan Press. For his own daily drives, he trusted Honda engineering, a six-cylinder motorbike and an aged Prelude coupé. Tyres were his other principal obsession.
Unlike Wittgenstein, he was not a trained engineer. His perorations on the qualities and variations of car tyres are, I understand from people who design them, more remarkable for their enthusiasm than for their technical accuracy. Sadly, therefore, when asked to explain the figures you read on the wall of your tyre, I succumbed to second thoughts and didn’t recommend Setright exotica.
It works as follows. The figures on my old Defender tyres read 235/85/R16. That means the width of the tyre measured from rim to rim is 235 millimetres. The figure 85 means that the depth of the tyre sidewall – height, if you prefer – is 85 per cent of the width. R means that the tyre is of radial construction, as most are. The figure 16 means that the diameter of the wheel on to which it has to fit is 16 inches.
Other figures refer to the date of manufacture – 2324 means the 23rd week of 2024 – and its load and speed ratings. But what I couldn’t answer was why the mixture of metric and imperial?
I turned to Setright. Doubtless he explains it somewhere but, I lost myself among his Gothic intricacies – until dear old Classic Car Buyer came to the rescue.
Tyres have to fit wheels; not any old wheel or future wheels, but existing wheels. Wheels are measured in inches because mass production emanated from the USA, which uses imperial.
In 1975, Michelin tried going metric with the TRX tyre, which required different wheel rims. Peugeot, Citroën and BMW dallied with metric but were defeated by the law of supply and demand: why would anyone make tyres that don’t fit any other of the world’s 1.644 billion vehicles? Best stay in inches.
I think Setright would have welcomed that. A man who could persuasively argue that the 1969 Fiat 128 was the most influential of popular post-1945 cars would have had no trouble reconciling imperial and metric.
