Flat Tyre: Essential Equipment to Keep in Your Car

A flat tyre usually strikes unexpectedly – often in the worst possible place at the worst possible time. The days when every car came with a full-size spare are long gone. Modern vehicles prioritise space-saving and offer alternative solutions, each with their own advantages and disadvantages. We explain which equipment actually helps with a puncture and what to bear in mind when it happens.

The Evolution of Spare Wheel Concepts

For decades, the full-size spare wheel was standard equipment in every car. In the boot floor or under the vehicle's rear was a full-size tyre that could be fitted in case of a puncture, subsequently enabling normal onward travel without restrictions. This concept had one decisive advantage: after the wheel change, the driver wasn't bound by speed limits or range restrictions.

The automotive industry has moved away from this concept for various reasons. Weight reduction to lower fuel consumption, space gains in the boot, and cost savings have meant that full-size spare wheels are rarely supplied as standard today. In their place have come space-saver wheels, tyre repair kits, and run-flat tyres. Each of these alternatives has specific characteristics that determine its application.

The space-saver wheel, often called a temporary spare, is smaller and narrower than regular vehicle tyres. It serves solely to reach the nearest garage and is subject to a speed limit of typically 50 mph. Longer distances or higher speeds can damage the space-saver and impair the vehicle's handling. Despite these limitations, it offers the advantage of enabling onward travel under one's own power.

Tyre Repair Kits and How They Work

Many current vehicles are delivered with a tyre repair kit instead of a spare wheel. These kits typically consist of a compressor and a sealant fluid. The principle is simple: the sealant is filled into the damaged tyre via the valve, then the tyre is inflated with the compressor. During driving, the fluid distributes inside the tyre and seals smaller damage from within.

The advantages of this system lie in its compact size and low weight. The entire kit fits in a small bag and takes up hardly any storage space. Additionally, use doesn't require a wheel change, which is particularly attractive for people who don't trust themselves to change a wheel or are physically unable to handle the heavy wheels.

However, the advantages are offset by considerable limitations.

Tyre repair kits only work with certain types of damage. Small punctures from nails or screws can be sealed, but larger tears or damage to the tyre sidewall cannot. With a blowout, the kit is ineffective. The temporary nature of the repair should also be noted: the tyre must be examined by a specialist garage promptly, and in many cases replacement is necessary since the sealant prevents permanent repair.

Run-Flat Tyres as a Modern Alternative

A technically more sophisticated solution is run-flat tyres. These special tyres have reinforced sidewalls that can bear the vehicle's weight even with complete air loss. After a puncture, continued driving is possible for a limited distance, typically 50 miles at a maximum of 50 mph.

The advantage of run-flat tyres lies in the safety of controlled air loss. With a conventional tyre, a sudden pressure drop can lead to dangerous vehicle behaviour. Run-flat tyres, by contrast, enable the vehicle to be brought safely to a stop and then driven under its own power to a garage. This characteristic is particularly valuable on motorways or in areas without breakdown assistance.

The disadvantages of run-flat tyres primarily concern ride comfort and cost. The reinforced sidewalls are less elastic than conventional tyres, resulting in a harsher ride. Road irregularities are transmitted more to occupants. Additionally, run-flat tyres are more expensive to purchase and cannot be fitted to every rim. Vehicles with run-flat tyres also require a tyre pressure monitoring system, as air loss would otherwise go unnoticed.

The Classic Wheel Change

Despite all modern alternatives, the classic wheel change remains a fundamental skill for drivers. Anyone with a spare wheel or needing to swap a damaged wheel for an intact one should know the procedure and have practised it. The necessary tools are found in most vehicles in the boot or under the load floor.

The jack raises the vehicle so the wheel hangs free and can be removed. Correct positioning of the jack is crucial: every vehicle has reinforced jacking points in the body that can bear the weight. Positioning at the wrong point can cause body damage or allow the jack to slip. The vehicle handbook shows the correct jacking points.

The wheel brace or wheel nut wrench is used to loosen and tighten the wheel nuts or bolts. Loosening occurs before raising the vehicle, as otherwise the wheel rotates with it. After raising, the nuts are completely removed, the wheel taken off, and the spare fitted. The wheel nuts are initially tightened by hand in a cross pattern to ensure even seating. Final tightening to the prescribed torque occurs after lowering the vehicle, ideally with a torque wrench.

Safety Aspects When Dealing with a Puncture

Dealing with a flat tyre at the roadside involves considerable danger from passing traffic. Securing the breakdown location therefore has highest priority, before the actual repair work. Putting on the high-visibility vest and setting up the warning triangle are the first actions after stopping.

The choice of stopping location significantly influences safety. On motorways, an emergency refuge area or services should be aimed for if possible. The hard shoulder should only be used in extreme emergencies and doesn't offer a safe working area. Anyone who must stop on the hard shoulder should drive the vehicle as far to the left as possible and bring occupants to safety behind the barrier.

On A-roads and B-roads, a clear spot with sufficient verge is the best choice. Bends, crests, and sections with poor visibility should be avoided. In darkness or poor visibility, requirements become stricter. The vehicle's lights should remain on, and additional warning lights increase visibility.

The actual work on the vehicle should be carried out promptly but without haste. A wheel incorrectly tightened under time pressure can come loose during driving, with potentially catastrophic consequences. Anyone who doesn't trust themselves to change a wheel or considers the situation too dangerous should call for professional help. The breakdown services of motoring organisations like the AA, RAC, and many insurers offer assistance that includes safe wheel changes by trained personnel.

Regular Checking of Breakdown Equipment

The best breakdown equipment is of little use if it's not ready for action when needed. Regular checking of available equipment should be routine for every vehicle owner. For spare wheels and space-savers, this primarily concerns tyre pressure. A spare wheel lying unnoticed in the boot for months or years continuously loses air and may no longer be roadworthy when a puncture occurs.

Tyre repair kits have an expiry date indicated on the sealant. After this date, the fluid's effectiveness can no longer be guaranteed. The compressor should be tested occasionally to ensure it works and the hose is intact. For vehicles with 12-volt connections, a test connection is advisable to rule out contact problems.

The jack also deserves attention. Mechanical jacks can become stiff through corrosion; hydraulic models can lose oil. A brief function test in one's own driveway provides certainty that the equipment works when needed. The wheel nuts or bolts should also be looseable with the supplied tool. Seized nuts can make a wheel change at the roadside impossible.