Beware of your spare
Motorists often breathe a sigh of relief when they find a spare tyre in their boot after experiencing a puncture. However, this relief may be short-lived, as the spare tyre could lead to other road risks.
Keith Phelps, Dunlop Tyres SA’s leading technical tyre expert, warns that the compact “biscuit” spare can pose serious dangers to drivers, passengers, and other road users if misused or poorly maintained.
“It’s not often that drivers need to pull out the spare tyre from the boot,” Phelps states. “For many cars, this trusty little biscuit tyre—so named for its size—sits unused. While we may enjoy not needing to use the spare, it is crucial that we don’t ignore it. As drivers, we must always prepare for emergencies by regularly assessing our spare wheel and using it correctly to avoid additional problems.”
Understanding the Biscuit-Sized Spare Tyre
The biscuit tyre, also known as a space saver tyre, is designed as a temporary emergency solution that enables a driver to reach the nearest service station or tyre shop for tyre replacement or repair. These compact spares are smaller, narrower, and lighter than standard tyres, helping to save space in the trunk. However, their limitations can make them unsafe for extended use.
Dangers of Using a Biscuit Spare Tyre for Too Long
- Reduced Traction and Stability:
The smaller tread surface area of a biscuit tyre leads to less grip on the road, particularly in wet or slippery conditions. This increases the risk of skidding or losing control of your vehicle—known as aquaplaning or hydroplaning—especially at high speeds or during sudden manoeuvres. Drivers should remain aware of road conditions and adjust their driving style accordingly. - Limited Speed and Distance:
Most biscuit spare tyres are designed for a maximum speed of 80 km/h and should not be driven for more than 60-80 kilometres. Exceeding these limits can result in blowouts, handling issues, and even tyre failure. Motorists should exercise caution, particularly when driving on freeways and in heavy traffic. - Braking and Handling Risks:
Because the spare is smaller and thinner than the regular tyres, it alters the vehicle’s handling characteristics, affecting steering and braking performance. This can be especially dangerous on freeways, where making emergency stops becomes more challenging. - Damage to the Car’s Suspension and Transmission:
Prolonged use of a spare tyre can cause uneven wear and additional stress on the vehicle’s suspension system, leading to costly repairs. In vehicles with all-wheel or four-wheel drive, using a smaller spare can also strain the drivetrain and potentially damage the transmission.
What Should Motorists Do?
- Replace or Repair the Damaged Tyre: The spare should only be used to get to the nearest service station.
- Follow Speed and Distance Recommendations: Never exceed the recommended speed or distance limits for a spare space saver tyre.
- Regularly Check Your Spare Tyre: A spare tyre that has been unused for years may be underinflated or deteriorated, showing signs of cracking in the tread or sidewall rubber. Such signs indicate that the tyre is no longer safe for use.
- Consider Investing in a Full-Sized Spare: If your vehicle has space for one, a full-sized spare offers a safer alternative in emergencies.
Stay Safe on the Road
“While a biscuit spare tyre can be a lifesaver in an emergency, it is not a long-term solution. Driving cautiously and replacing your damaged tyre as soon as possible can help prevent accidents, vehicle damage, and unnecessary risks on the road,” concludes Phelps.