Safety is the most important aspect of tyre management and correct tyre pressure is the most crucial element, yet it’s also one of the most overlooked checks by drivers. Checking with an accurate gauge is vital as the ones on garage forecourts can vary.
The correct pressures for the car’s tyres are in the handbook and this will also explain what pressures the tyres should be inflated to for different driving conditions, such as high speed motorway driving or when fully loaded for a holiday.
Tyre pressure also plays a huge part in the handling and efficiency of cars.
The pressure a tyre is inflated to has a major effect on its rolling resistance, which affects acceleration, braking, cornering, fuel consumption and emissions – almost every facet of the way a car behaves.
Contrary to popular belief, an under-inflated tyre is the most dangerous situation to leave unattended.
This is because an under-inflated tyre will run hot due to friction and it will be more prone to a blow-out.
As many cars now do not have a spare wheel as standard or have a space saver that dictates a 50mph maximum speed, this can seriously impact on a fleet driver’s ability to travel safely to a destination within the required time.
There is also the added problem that an unexpected blow-out can lead to a vehicle being off the road while a replacement tyre is sourced and fitted.
As part of your tyre checks, take time to look at the valves as they can let the tyre deflate slowly over time if they have been incorrectly fitted, become damaged or worn through age.
Look for damage to the tread and sidewalls, anything that may cause a puncture and check the tyre is wearing evenly across its whole width.
The legal minimum tread depth for a tyre in the UK is 1.6mm across three quarters of the width of the tread, which you can check either with a tyre depth gauge or simply by looking at the wear indicators moulded in between the treads of the tyres itself.
This tread width has to extend the entire circumference of the tyre. Remember that tyres begin to lose their optimum performance before they reach the minimum required by law.
Choosing the right tyre
The correct tyre for the job sounds obvious, but it can often be overlooked if a company fleet is looking to save money.
A spread of different tyres may share the same size and speed rating, but a more expensive tyre may work out the more cost-effective option due to reduced fuel consumption.
Goodyear data shows the difference between the best and worst tyres can be as much as 7.5% in fuel economy.
There is also evidence from Goodyear that many tyres that are a little more expensive to fit initially soon repay the extra expense with longer life, reducing the overall cost to replace.
If you spot uneven tread wear during a regular tyre check it is a symptom of a more fundamental problem.
The most likely cause will be incorrect wheel alignment, often caused by the wheel being kerbed during parking. Even the slightest parking knock can affect wheel alignment.
An unevenly worn tyre is more susceptible to deflating unexpectedly, so don’t ignore it.
Usually, uneven tyre wear is spotted on the inner or outer edges of a tyre, though incorrect tyre pressures can also lead to irregular wear.
Uneven tyre wear can result in police action if the car is found to be beyond safe limits, meaning a possible three penalty points and a fine of up to £2,500 per tyre, and also more downtime for the vehicle.
Tyres account for around 35% of a car’s overall maintenance budget, so prolonging the healthy life of tyres is sound practice.
Run-flat tyres are popular and have now moved into their third generation.
Run-flat tyres were originally criticised for the negative impact they had on a car’s ride quality due to the extremely stiff side walls required for the tyre to retain its shape when punctured.
But the latest versions offer the same comfort as normal non-run-flat tyres.
The major benefit of run-flat tyres for fleet users is the vehicle can be driven to a safe place for the tyre to be replaced.
It also means the driver has more choice in when and where the tyre is replaced which in turn means much less time wasted for car and driver waiting for a new tyre to be fitted.
If you experience a puncture while driving, it can often be company policy to have the wheel and tyre replaced by a professional fitter to prevent future damage or accidents (a recent Fleet News poll revealed that 45% of companies don’t allow staff to change flat tyres).
With many cars now not fitted with a spare wheel and tyre, this decision is taken out of the individual’s hands.
Many carmakers choose not to fit a spare wheel to save space and weight to improve fuel economy and emissions.
Don’t mix tyres
Never mix different tyres together, whether this means winter and summer tyres on the same axle or varying sizes or types of tyre from front to rear.
While tyres with the same size, speed and load ratings may have different tread patterns, they will behave in much the same way, but tyres for different purposes used on the same vehicle will lead to unpredictable behaviour.
Size, width and depth
Understanding the numbers on your tyres will help you make an informed decision about replacements. The markings are there to inform you of the tyre’s size, width and the depth of the sidewall.
It will also tell you what speed and load ratings the tyre has, which is important for any vehicle likely to carry heavy items. For some cars, asymmetric tyres will be required, which are tyres that can only be fitted in one direction and specifically on left- and right-hand sides of the car.
Summer vs winter
The right tyre for the conditions could mean a switch to a set of winter tyres for many company drivers.
There is an added cost to fitting winter tyres and storing the summer tyres, plus the refitting the following spring, but these costs can be offset.
The reduced wear on both sets of tyres means the cost of replacements is spread out over a much longer period, plus fleets will suffer fewer accidents in cold weather if the vehicles are using winter tyres, so repair costs and unnecessary downtime are both reduced.
Winter tyres are designed to work at their best when the temperature gauge reads 7°C and below. The reason for this is when the air temperature is at 7°C, the ground temperature will most likely be at 4°C and this is when frost begins to form on road surfaces.
Tyre pressure systems
Tyre pressure monitoring systems (TPMS) will soon be required by law on all new cars from November 2012 across the whole of the European Union.
The safety benefits of TPMS are obvious and considerable as they can alert the driver to a potentially dangerous situation before it becomes a hazard.
For fleet managers, TPMS brings its own challenges as the valve fittings can be very sensitive and replacements expensive.
No standard TPMS system is used across all types of car. However, Kwik-Fit Fleet has a service to ensure TPMS is working properly.
For some fleets operating vehicles of three-years old or more, this is essential as the TPMS dash warning light could mean an MOT failure under new rules that fails any car with warning lights visible.