The Venerable Bead: How the Professionals Change Car Tyres

In the past, people used to change car tyres by hand. Some still might but this arduous procedure has been semi-automated for a long time. Here’s how professional tyre fitters change a car tyre, using a tyre machine.

As the tyre to be replaced will probably have been in service for a long time, it’ll be reluctant to part from its wheel. The beads, where they abut the wheel, will be firmly stuck and this is where the tyre machine’s first weapon comes into play. After unscrewing and removing the valve to let the air out of the tyre, the fitter will position the wheel in the jaws of the bead breaker. One press of a pedal and the bead is ‘broken’ – separated from its location.

Next, the fitter will lay the wheel flat on the tyre machine, clamping it into place. Since wheels – especially alloy ones – are both delicate and expensive, the equipment is designed to not touch the wheel rims directly. Having levered the upper bead upwards over the wheel rim, the fitter will engage the hooked head of the tyre machine under the bead. Another pedal press sets the machine rotating, to skin the tyre off the upper rim. Repeating this process for the lower bead separates the old tyre from the wheel.

A little preparation of the wheel comes next. The old valve body is sawn off inside the wheel and if necessary, the inner faces of the wheel rims are cleaned. The old wheel balancing weights are removed. Having pulled a new valve into place with a special tool, the fitter will coat the wheel rims and the new tyre’s beads with a special compound. This is a lubricant that eases the fitting process though sometimes, a material with sealing properties may be needed.

The penultimate stage of tyre fitting is essentially the reverse of the removal of the old tyre. The fitter uses the tyre machine to force the new tyre on to the wheel, bead by bead. Finally, a compressed air line is used to inflate the tyre, until its beads pop outwards to seal against the inner faces of the wheel rim. Throughout the process, the tyre fitter has done the controlling, while electricity and compressed air have done the heavy work.

This leaves just the wheel balancing. The fitter will have already positioned the tyre correctly in relation to the wheel, using a coloured dot marking on the tyre. However, balance weights are virtually always required and there’s a machine to help with this task. The tyre fitter will clamp the wheel onto the machine. When the guard is closed and the machine starts, it will take the wheel up to a fixed speed, usually about 200 revolutions per minute.

Using its onboard sensors and electronics, the balancing machine points out where the wheel weights should be fitted and how much they should weigh. Having fitted the weights – stick-on or clamp-on as appropriate – the fitter will run the machine once more, fine-tuning the balance with other weights if necessary.

As we can see, what used to be an hour or more’s hard work is done in minutes. What’s more, if you watch the proceedings from the waiting area, you’ll know exactly what’s happening in the tyre bay!

Merityre are a leading UK independent supplier of car tyres. Why not visit their website at www.merityre.co.uk and see where you can buy your next set of tyres.