Guidance on Uneven Tread Wear
Often car tyres need to be replaced before their specified life has been reached mainly because of rapid or uneven tread wear. The most common causes of avoidable tread wear are:
- Under-Inflating - Causing rapid wear along the edges of the tread.
- Over-Inflating - Causing rapid wear along the centre of the tread.
- Faulty brakes or shock absorbers - Can cause flat spots around the tread of the tyre.
- Incorrect wheel alignment (tracking) - can cause rapid wear along the inside or outside edges of the FRONT tyres. If you strike a kerb or hit a pot hole - the delicate settings of the steering geometry may become misaligned resulting in uneven wear. Wear and tear in the steering components can also affect wheel alignment so it's worth having your front wheels realigned every 6000 miles.
A tyre condition check should be carried out frequently to look for signs of wear and tear. The tyres are in constant contact with the road shouldering all of those bumps and knocks under the weight of the car and is therefore a critical safety aspect.
What to check and why:
The shoulders of your tyres are the outer and inner edges. If you notice that they are wearing more rapidly than the central belt this could be due to under-inflation. Under inflated tyres can cause performance issues, specifically with breaking and increase your fuel consumption.
Over-inflated tyres cause the centre of the tyre to wear more rapidly than the rest of the tyre. Over-inflated tyres can be dangerous as well as they increase the risk of a blow out, affect the cars ability to break and again can increase fuel consumption.
To check the recommended tyre pressures for your car, simply enter your registration into our tyre pressure checking tool.
Tyres that have only worn on one side are symptomatic of incorrect camber alignment. Camber alignment is the angle of the tyres which can be viewed from standing in front of the car. The tyres should be positioned vertically, if they angle inwards (negative camber) or outwards (positive camber) then they are misaligned.
Tyres that wear in one place only is referred to as spot wear. The main causes of this are faulty suspension components.
Diagonal or cupping wear as it is sometimes referred to is the wearing of the tread in several patches, usually in a diagonal pattern usually due to faulty suspicion components, incorrect wheel alignment or unbalanced tyres.
Feather- edge wear if the ‘feathering’ of the tread blocks on a tyre, often caused by positive or negative camber alignment.
Tread wear can be identified due to the tyres in-built tread wear indicator. Tread wear indicators are rubber bars across the central belt of the tyre, once your tyre wears down to the same level as the tread wear indicator it is time to replace your tyres.
It is important to remember that not only are faulty tyres unsafe but it is also a legal requirement to ensure that you have the correct type and size for your car, the tread depth is no lower than 1.6mm and the tyres are inflated to their recommended tyre pressures. Illegal tyres could cost you £2,500 per tyre and three points on your licence.
Related: When should I replace my car tyres?
Providing the tyres are legal and in good condition you can help prevent uneven wearing by having them rotated. This is a process whereby tyres are removed from the vehicle and swapped front and rear and should be carried out after driving on the tyres for around 6,000 miles or every 6 months whichever is soonest.
How the tyres are rotated will depend on the type of vehicle you have.
- Front wheel drive – the front tyres should be moved to the back on the same side of the car, so front drivers side is moved to back drivers side. The back tyres are moved forward but on the opposite side so the rear drivers side is then fitted to the front passenger side and the rear passenger side is fitted to the front drivers side.
- Rear wheel drive – the reverse of the front wheel drive is implemented. The two rear tyres are moved forwards on the same side and the two front tyres are moved to the rear but across from the driver side to passenger side and visa-versa.
- Four-wheel drive – the front passenger side is moved to the rear driver side and the front drivers side is moved to the rear passengers side.
- Directional tyres – if you have directional tyres fitted to your vehicle then the tyres need to be fitted to the same side they were removed from i.e. tyres on the front passenger side must be moved to the rear passenger side and tyres on the driver side must be moved from front to rear only and not across to the passenger side. The reason for this is that directional tyres have been designed to be fitted on a specific side and could be dangerous if swapped across.
Rotating the tyres helps them wear more evenly, providing a smoother ride and prolonging their lifespan.
Cuts, breaks and abrasions can penetrate deep into the inner fabric of your car tyre which can be dangerous, even capable of causing high speed blow-outs. However, penetration of the tread by a nail or shard of glass or metal can often be safely repaired.
At National Tyres and Autocare only a special vulcanised plug patch is used which repairs the tyre to high standard in accordance with NTDA and BSAUl59 regulations.
To keep the tread in constant contact with the road, the wheel and tyre have to be correctly balanced. If the vehicle was to be raised on a jack and the wheel spun by hand, an unbalanced wheel would always stop at the same point - with the heavier imbalance being of course at the bottom of the wheel.
On the road, wheel imbalance can actually lift the tyre from contact with the road creating vibration through the steering wheel, causing steering and braking problems. This vibration causes high-pressure stress in the steering, hub assemblies and suspension, resulting in excessive mechanical wear and high fuel consumption as well as tyre wear. Damage to the suspension, wheel bearings and steering components is unavoidable if the imbalance is left unattended.
Incorrect wheel balance is easily corrected by using a computerised electronic wheel balancer to measure the imbalance, and then adding small metal weights to even things up. It is essential that you have your wheels balanced whenever you replace a tyre or have a puncture repaired (alloy wheels require specially coated weights to avoid corrosion caused by chemical reaction between differing metals).
Corner balancing often referred to as weight balancing involves adjusting the suspension to achieve an even weight distribution over the four wheels to ensure that the vehicle handles evenly in left and right turns.
The vast majority of vehicles do not require corner balancing as there is no provision for adjusting the spring height. In any case, it would take a huge imbalance in spring height to have any significant effect on corner balance.
Some high performance and race cars do require corner balancing to maintain their handling and performance characteristics. This is a specialist job and requires constant spring height adjustments, with the correct weights in the vehicle and using a Corner Balance Equation to bring any imbalance to an acceptable low level.
National does not offer this service and recommends that corner balancing is carried out by the vehicle manufacturer.
Everything you should understand about Tyre Pressure
Checking your vehicle's tyre pressures is easy!
It's easy to check your vehicle's tyre pressure, and you can carry out the check at home free of charge in just a couple of minutes.
The first step is finding the correct pressure rating for your vehicle. These can be found on your vehicle in the following places:
- Your car or truck's manual
- Printed on the inside ledge of the driver's door
- Inside the petrol cap
The correct pressure setting is determined by the manufacturer of your vehicle and is different depending on the make and model of each vehicle. If you are unable to locate the recommended pressure, use this tyre pressure web link. Simply type in your registration plate and the link will provide your recommended pressure.
When you locate the pressure chart for your vehicle, you will find that pressure varies depending on the weight of your load. e.g . when you're travelling alone, the pressure should be different from when your vehicle is loaded with family, baggage etc.
Example tyre pressures for a Volkswagen Polo, 5 door hatchback;
|Tyre Size||Front Tyres||Rear Tyre|
|165/70R14 T 81||2.3 BAR / 34 PSI||2.1 BAR / 31 PSI|
|175/65R14 H 82||2.3 BAR / 34 PSI||2.1 BAR / 31 PSI|
|185/60R14 H 86||2.1 BAR / 31 PSI||2.1 BAR / 31 PSI|
|195/50R15 H 82||2.3 BAR / 34 PSI||2.1 BAR / 31 PSI|
MEASURING YOUR TYRE PRESSURE
To test your tyre pressure, you need an accurate pressure gauge. Take off the dust cap on the valve, fix on the pressure gauge and take a note of the result. If your tyre needs extra air, you should inflate it using an air pump at home, or use the facilities provided in many petrol stations. If the tyre is overinflated according to the pressure chart, you can allow air to escape whilst the dust cap is off.
When your tyres are at the right pressure, take off the air pipe, make sure there's no dirt in the valve, and re connect the dust cap.
If you're not happy carrying out a pressure check at home, for instance if you don't have the proper equipment or aren't confident at checking the levels, then staff at National Tyres and Autocare will be delighted to help – just pop along to your local branch for a no-cost check.
DIFFERENT MAKES OF PRESSURE GAUGE
There is a wide range of makes available to buy online or in high street shops like Halfords. Costs range from below £5 to £25 depending on the manufacturer. Some are produced by safety organisations like the AA or tyre brands like Michelin.
BAR PRESSURE VS PSI PRESSURE
There are two different measurements to record tyre pressure – bar or psi. If your gauge doesn't match the reference in your handbook, then it's easy to change measurements by using this website link: Find your recommended tyre pressures
WHY TYRE PRESSURE MATTERS
Having the right tyre pressure may help prolong the life span of your vehicle's tyres, increases the vehicle's safety and helps save fuel.
TYRE LIFESPAN - TREAD WEAR
A tyre's life-span may be decreased by up to 75% if the tyre is operating at around 80% of the optimum pressure. However, if pressure drops to 60% (surprisingly, this isn't unusual), tyre lifetime may be decreased up to 35%. If your tyres are wearing out fast on the outer edges, this can be an early indication of possible under-inflation.. Take action, because if this problem is left unattended, this may soon result in your tyres becoming illegal.
VEHICLE SAFETY - BLOW-OUTS
Blow-outs can be caused by tyres which are under inflated. When this happens, there is insufficient air to hold up the vehicle's weight. This causes the sidewalls to be compressed by the vehicle's weight resulting in them flexing over their regular limits. This kind of abnormal flexing can cause a build up of heat in the tyre and significantly raises the likelihood of a blow out.
IMPROVED FUEL REQUIREMENTS
When tyres are under inflated, there is a greater proportion of tyre tread touching the surface of the road. This causes an increase in friction which slows the tyre as it rolls along the road. You you may hear this referred to as increased rolling resistance). What this means is your vehicle has to use far more power when driving on under inflated tyres, resulting in an unavoidable rise in petrol/diesel use. As well as being an added expense to you, this can also have a detrimental impact on the environment as the more fuel you use, the higher the levels of carbon dioxide are emitted from your car – so the correct pressure can help save money as well as the environment.
In conclusion, maintaining your tyres at the correct pressure could increase the lifespan of your tyres, improve the safety levels of your driving, and also benefit your wallet as well as the environment.
TOP TEN TYRE PRESSURE GUIDELINES
- Carry out a tyre pressure check at least once per month, prior to all trips and when you vary the vehicle's usual load.
- Tyres must be cold when you carry out the check - preferably when they've driven under two miles.
- Get the right pressure reading from your vehicle manual, driver's door ledge, petrol cap or using the online search above.
- Change the pressures as shown in your vehicle's manual when the vehicle is fully loaded (for instance, when you load your car up for family holidays).
- Use a dependable gauge to measure your pressure.
- Remember to examine all of your tyres not forgetting the spare one!
- Don't forget to check any towed vehicles, e.g. trailer/caravan/horsebox.
- During your pressure check, give your tyre a visual check for tread wear or problems like slashes/cuts/bulges.
- Pressure decreases more rapidly in warmer weather, so make sure you check tyres frequently in summer time.
- If uncertain, talk to qualified staff at your local National Tyres and Autocare.
RUN-FLAT TYRES AND PRESSURE
Run-flat/self supporting tyres are tyres which have been specially manufactured so they are able to keep driving for a short period following deflation, i.e. they will still work without air pressure. The sidewalls of the tyre are specially reinforced with specialised inserts which are strong enough to carry the vehicle's weight even if the tyre has absolutely no air pressure.
Typically, you will be able to drive your vehicle for at least fifty miles at an average speed of 30mph following deflation using run-flat tyres. However, this depends on conditions like your vehicle's load, speed and motoring conditions.
It is critical that vehicles using run-flat tyres have a special system installed to constantly measure tyre pressure, as it is generally impossible to sense a pressure change in this type of tyre. This system is known as TPMS - Tyre Pressure Monitoring System – and if you are towing a vehicle with run-flat tyres, then again, this vehicle must be equipped with TPMS.
TYRE PRESSURE MONITORING SYSTEMS (TPMS)
Certain new cars, such as Citroens andPeugeots , come with a built in TPMS. The Tyre Pressure Monitoring System continually tracks the pressure and temperature of tyres, warning the motorist of any problems as they occur. The system runs constantly, providing a near instant warning of any kind of problem with the vehicle's tyre pressure.
This benefits the motorist in many ways:
- No need to manually check tyre pressure
- Lower wear on tyres as they operate at correct pressure
- Lower fuel use
- Decreased likelihood of early tyre failure
Further to European Parliament laws, after November 1st 2012, TPMS will be installed as standard on all new cars sold within the European Union. Tyre safety bodies estimate that as much as 90% of vehicles using UK roads drive with incorrectly inflated tyres resulting in greater petrol/diesel use as well as quicker tyre wear. On your typical family saloon, a mere 6psi decrease in pressure results in a 20% rise in fuel requirements as well as a 30% increase in tyre wear. However, this reduction in tyre pressure would hardly ever be detected during usual driving conditions.
Advantages of maintaining correct pressures include: increased safety through superior handling, shorter braking distances, reduced chance of aquaplaning, lower tyre wear, lower fuel requirements and reduced carbon dioxide emissions. It is estimated that by the end of 2012, over 4 million cars driving in the UK will be fitted with TPMS.
The majority of detectors have an expected life of about seven years. The correct equipment and procedures must be used to reconfigure the replacement/new sensors in to the vehicle's on board diagnostics. For example, installers will have to ensure that the Tyre Pressure Monitoring System is functioning before working on a motor vehicle, and will have to appraise the status of every sensor and provide alternatives to the customer when a sensor approaches the end of its life.
TO WHAT SETTING SHOULD PRESSURE BE SET?
The LO level of the system can be set from 20 psi to 40 psi. It is recommended that the LO level is set at five psi under the maker's recommended pressure. In the case of a car's pressures varying front to back, the LO level should be set to four psi under the lower pressure. The HI level of the system can be set from 30-60 psi. As tyre pressures often rise by between 4-8 psi on a normal journey, it is recommended that the HI levels are set to 10 psi over the manufacturer's recommended pressure.
When a car's pressures vary front to back, the HI level should be set to 10 psi over the higher pressure.
FROM SOLID TYRES TO INFLATED TYRES – A SHORT HISTORY
Prior to 1895, motor vehicles ran on solid tyres rather than inflated pneumatic tyres. The first really functional pneumatic tyre was created by John Boyd Dunlop, and was first used on Michelin cars in 1895, heralding a comfier ride for all motorists!
Checking tyre pressures is simple, often free and only takes a few minutes. Your recommended pressures will be printed in your vehicle's handbook or stamped in the sill of the driver's door or can sometimes be found inside your fuel cap.
If you're having difficulty locating this information, why not use our simple tyre pressure checker, simply enter your vehicle registration number and take a note of your pressures.
If you don't have your own pressure gauge (we would always recommend buying one) or can't find a tyre pressure machine at a local petrol station, why not bring your car along to any National Tyres and Autocare branch and we'll check and adjust them FREE of charge.