TORQUE SHOP #10
This is the first Q&A session in our threepart series that “torques” about tyres.
When is it a good time to change tyres – every three years, or after clocking 30,000 kilometres? The best gauge would be the wear indicator, a raised nub found between the main grooves of your tyres. Once the tyre surface is level with the indicator, it is time for a change. It does not matter when this happens or after how many kilometres of driving.
But if your car has clocked 30,000 kilometres and the tyres have not reached the wear indicator, you should still consider changing them, because the rubber may have hardened and grip may be compromised. Do not scrimp on tyres, because you never know when you will need maximum performance from them. If I want to change only two tyres and keep the other two, should I install the new ones in the front or rear? We can imagine only a couple of reasons why you would end up with a pair of half-worn tyres and another pair of completely worn ones.
In all likelihood, you did not bother to rotate them as instructed in the car manual. And now you want to compound the problem by keeping the old, halfworn ones. The other reason might be that you managed to puncture two tyres at the same time, which is quite a rare thing to happen.
If you ever have to replace just a pair, the rule of thumb is to install the new tyres at the rear, because losing grip at the rear is dangerous for the average driver.
But if you can, replace the whole set and remember to rotate the tyres regularly. 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
DO NOT SCRIMP ON TYRES, BECAUSE YOU NEVER KNOW WHEN YOU WILL NEED MAXIMUM PERFORMANCE FROM THEM.
if the wheel was misaligned. Instead, the tyre had irregular bumps on its 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 were 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 suspension’s dampers are worn, a road hump, for instance, would cause the car’s 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 of your car’s rear dampers as soon as possible.
There is a lot riding on the tyres of a car, such as safety, comfort and control, so do replace them whenever necessary.