Q. My Citroën C5 recently failed its MoT test because two months earlier the Michelin Primacy tyre I’d had fitted to the nearside front wheel had been put on the wrong way round. The testing station rectified this, but just how dangerous could it have been?
SH, Bourne, Lincolnshire
A. As are many modern tyres, the Primacy is asymmetric, which means the tread pattern is not the same across the width of the tyre. This is because each side of a tyre has a different job to do: the outer part of the tyre tread is designed to take the strain when the car is cornering or steering, while the inner part is designed to expel water to lessen the chance of a skid.
Michelin therefore gives the outside of the tyre a denser, zigzag-type tread pattern to provide extra grip and durability, while the inner section will usually have a more widely spaced grooved tread pattern around the rim to help channel water away, particularly under braking.
According to a spokesman for Michelin, it probably would not be unsafe to use the tyre the wrong way round, but it certainly wouldn’t perform as well as it should.
In your case, because the fitting error was spotted so soon, it’s not likely any harm has been done to the tyre. But to be sure, inspect both front tyres, looking for any obvious difference in the way they are wearing. If you find obvious unevenness, you might want to contact the firm that fitted the tyre with a view to being compensated.
Dave Pollard has written several Haynes manuals and has tested just about every car-related accessory – read more from Dave here.
GOT A PROBLEM?
Email your question to firstname.lastname@example.org or write to Car Clinic, Driving, The Sunday Times, 3 Thomas More Square, London E98 1ST, with a daytime phone number, your address and as much detail about your car as possible. We can’t reply in person, so don’t send original documents or SAEs. Advice is given without legal responsibility.