“Oversteer is unpredictable, and most drivers are not trained to understand it. They may experience it first in a moment of panic, for example swerving to avoid someone stepping off a curb, or a car coming out of a junction,” he says.
Trying the third car fitted with just one new tyre on the right front was even more revealing, and arguably the most alarming scenario. Turning right, the car was inherently stable as the evenly worn left-hand tyres held traction until the car’s nose drifted wide into gentle understeer, easily controlled by lifting off the throttle.
Turning left, however, was a different story. The new front tyre gripped better than the worn rear, launching the car into oversteer. As Porteous pointed out, in this scenario, even the corrections become unpredictable; lifting off the throttle corrects the understeer when turning right, but the same driver response could worsen the effect of oversteer when turning left.
The lessons to be learned are obvious. Regardless of what you may be told by a garage, tyre fitter or even your company-car fleet manager, any new tyres must go on the rear axle with partly worn treads moved to the front. As Porteous told us: “That’s what I tell my family, and my advice to anyone else would be to insist on it.”
Michelin and the future of tyre tech
The Michelin brothers got their start in the tyre business after patenting a removable pneumatic bicycle tyre in 1891, and were the first company to offer similar pneumatic tyres for motor cars. We’ve been riding on air ever since, paying the price for the smoother ride with the risk of punctures.
