Temporary spare wheels should be used within their restrictions as they are not designed for typical speeds or prolonged usage.

“The benefits of a temporary spare wheel are reduced weight and size (width),” says Hiroshi Nakanishi, Bridgestone’s General Manager for Field Engineering and Technical Services. “The lower weight contributes to reduced fuel use over the vehicle’s lifetime, and the smaller size (width) is used by motor manufacturers to allow more luggage space in the boot.”

However, Nakanishi explains that the benefits of these tyres also come with restrictions. They are often considerably narrower than the full-size tyres on the vehicle. This reduces their road holding ability.

Temporary spare wheels are also sometimes fitted to a smaller diameter rim and thus have a smaller overall diameter than the car’s standard road wheels. If a temporary spare is fitted to the drive axle with a full-size wheel opposite, the car’s differential compensates for the difference in diameter between the spare and the full-size wheel. Over long periods, this can cause excessive wear to the differential.

The difference in width and tread pattern can also reduce braking performance and may cause the vehicle to pull to one side under braking. Apart from the safety concerns, a temporary spare wheel is not designed for continued use and will wear out rapidly.

“A temporary spare wheel allows a journey to be completed so that the vehicle can have the damaged or punctured tyre repaired or replaced,” Nakanishi states. “Temporary spare wheels should not be used for extended periods.”

He adds that most temporary spare wheels are restricted to 80km/h and advises motorists to avoid travelling at higher speeds. “A temporary spare wheel will not provide the braking and road holding capability of a vehicle’s usual tyres. We advise motorists to use temporary spares at moderate speeds as a ‘get me home’ feature. They should not be used for prolonged driving,” he concluded.