Motorists often put tyres to the bottom of the list when budgeting for car maintenance, and yet a car’s tyres provide the only contact between the vehicle and the road, making them essential to road safety. Department for Transport figures reveal that illegal, defective or under-inflated tyres were a contributory factor in the death of 43 motorists in 2007, and played a part in a further 984 accidents. New research conducted by TyreSafe found that more than half of motorists surveyed admitted to not checking their tyre pressure in the last month, the maximum period recommended by TyreSafe between checks. This negligence is reflected further in MoT failure rates, with 1.1 million failures recorded in 2007/8 as the result of tyre defects, the fourth most common reason for an MoT failure.
Function of the tyre
Tyres play a fundamental role in the performance and handling of a car. Its main functions are to contain a pressurised volume of air in order to carry the weight of the vehicle and its load, to transmit traction and braking forces to the road surface and to keep the vehicle stable when cornering. The tyre also acts as a spring to supplement the vehicle’s main suspension system.
Poorer vehicle performance
Driving on under-inflated tyres has a significant adverse effect on vehicle handling. Under-inflated front tyres can cause understeer or a reduced ability to corner properly, while under-inflated rear tyres can lead to oversteer, where the back end of the car loses grip and slides out towards the outside of a turn, potentially throwing the car into a spin.
Drivers are often unaware of under-inflation as it can occur over an extended time period, therefore TyreSafe advises checking pressures at least once a month and before a long journey. Driving on under-inflated tyres causes heat to build up inside the tyre, as the tyres require more energy to do their job. Motorway travel on under-inflated tyres can often be particularly dangerous, as heat can build to excessive levels over a long distance, potentially causing a blowout. Tyre failures of this kind are highly dangerous as the vehicle is difficult to control, and the resulting tyre debris on motorway carriageways can often lead to further accidents. Motorists towing caravans or trailers should also be careful to check and adjust tyre pressures prior to setting off on a trip, as extra pressure may be required to support any additional load.
Reduced running costs
In addition to the important implications for road safety, under-inflated tyres can also add financial costs, as driving on under-inflated tyres causes uneven wear towards the outside edge of the tread, which can lead to premature replacement. Research conducted by a major tyre manufacturer and TyreSafe member reveals that by running tyres at just 80 percent of the recommended pressure, motorists can expect tyre life to be reduced to around 75 percent. If the pressure falls to 60 percent, which is not uncommon, motorists can expect to achieve just 35 percent of the potential mileage from the tyre.
Under-inflation also affects fuel economy, with research revealing that a tyre under-inflated by 10psi increases fuel consumption by approximately 2.5 percent. Keeping tyres correctly inflated helps motorists to maximise fuel efficiency and minimise CO2 emissions.
Helping motorists stay safe on the roads
In order to help educate motorists on the practicalities of correct tyre maintenance, TyreSafe has added a set of ten easy-to-follow, digitally animated tyre safety lessons to its website. The lessons are designed to inform motorists about tyre wear and tyre pressure, and cover all aspects of tyre maintenance, providing the viewer with a clear explanation of how to measure tyre pressure and tread depth, together with advice about tools and cost implications.
Top tips for checking tyre pressure
1. Check your tyre pressure at least once a month
2. Check the vehicle manufacturer’s recommended level for your vehicle
3. Check when tyres are cold (i.e. when you have travelled less than two miles)
4. Tyre pressures should be adjusted according to the load or number of passengers being carried
5. Use a reliable and accurate pressure gauge
6. Check the pressure in all four tyres as well as the spare tyre
7. Check the general condition of tyres, removing any embedded objects and looking out for bulges, cuts or lumps
8. If unsure, take your vehicle to an approved fitting centre and speak to the experts.