Wheels, a bit like tyres, aren’t something most of us spend much time worrying about. But having correctly balanced wheels can make a big difference to how comfortably your car rides and how quickly components like tyres, steering and suspension joints wear out. Here’s all you need to know about having your wheels balanced.
How do you know when your wheels are out of balance?
As your speed exceeds around 40mph, you might notice the steering wheel start to wobble in your hands. The faster you go, the greater this vibration becomes, to the point where it can be quite uncomfortable to hold the steering wheel, or – if it’s rear-wheel drive – the car feels as though it’s shuddering slightly.
What is the result of unbalanced wheels?
As well as the unpleasant vibration, an unbalanced wheel will cause the tyre on the effected wheel to wear unevenly. It could also affect your suspension and steering, causing wear that you won’t know about until it comes to light, either when your car fails its MOT or when it’s highlighted by a garage during a regular service.
Doesn’t a vibration mean a new wheel or tyre?
Just because you’ve got excessive wheel wobble, it doesn’t always mean you need a new wheel. In order to spin perfectly, a circular object needs to weigh the same the whole way round. Things like the hole cut in the wheel for the valve stem to poke through and tiny variations in the thickness of the tyres mean that a wheel is never perfectly balanced on its own. And the balance changes as tyres wear down. The result is that wheels need to be ‘artificially’ balanced.
How are wheels balanced?
Garages, especially those focusing on selling tyres, have machines that spin the wheels and use a computer to tell the technician exactly where weights should go to correct any imperfections.
What sort of weights are used?
When virtually every car had steel wheels, they used to employ what are called ‘knock-on’ lead weights which were hammered onto the wheel rim. However, those aren’t great for alloy wheels so most of the time adhesive non-lead weights are used for wheel balancing. If a garage does use ‘knock-on’ weights on an alloy, they should be on the inside of the rim.
When should you get wheels balanced?
Aside from if you have a vibration, any quality tyre retailer should balance your wheels when they fit new tyres because new rubber will send the wheels out of balance. They shouldn’t charge anything for this.
What if wheel balancing doesn’t cure the vibration?
Having your wheels balanced will stop the wobbling caused when the natural weight distribution isn’t quite right. What having wheels balanced won’t do is compensate for a bent wheel (that can happen when a car hits a pothole) or tyres that have had one particular area of tread scrubbed off more than anywhere else (that can happen when people perform handbrake turns). So if you have your wheels balanced and the vibration persists, you need to investigate further.
Why is wheel balancing important?
Think back to when you were a little kid playing with spinning tops or rolling hula hoops. The most satisfying goes ‑ and when your top or hula hoop ran under its own steam for the longest ‑ were when you got the spin just right and the toy was perfectly balanced. The difference between these toys and cars is that road wheels rotate at a much higher speed. A 15-inch wheel will rotate around 2100 times every mile so a wheel that’s out of balance and wearing one area of the tyre more than it should will quickly cause lasting damage.
* Nick Reid is a fellow of the Institute of the Motor Industry and head of transformation at Green Flag