Torque Shop

Just four months after I replaced all four tyres on my car, I started to feel some vibration from the rear.

When I checked, I noticed one of the rear tyres had an unusual wear pattern.

It was not worn on one side, as would happen if the wheel was misaligned.

Instead, it had irregular bumps on the tread all along the circumference.

I took it back to the tyre shop, assuming it was defective.

However, the shop insisted the wear was due to a faulty suspension. The other three tyres are fine.

What could be the cause?

The wear pattern you describe is a clear indication of a worn damper.

While the spring in a suspension absorbs the shock from road irregularities, it is the damper (commonly but erroneously referred to as the "shock absorber" or "shocks") that checks excessive body movement.

When a car's dampers are worn, a road hump, for instance, would cause the body to bounce on the springs over several cycles. In fact, the oscillations may continue if there are further road irregularities. Dampers "dampen" the excessive bounce.

In your car, the tyre in question was forced to continuously bounce on the road surface, causing the intermittent circumferential wear.

You should replace the tyre and both your rear dampers as soon as possible.

SHREEJIT CHANGAROTH

A version of this article appeared in the print edition of The Straits Times on October 08, 2016, with the headline 'Torque Shop'. Print Edition | Subscribe