The tyre is the only contact between the vehicle and the road. For this very fact alone it stands to reason that your car’s tyres should not only be safe, but also hard-wearing, made from high quality materials, be durable and still provide you and your family with a comfortable drive. Together with ancillary insurance products such as their car warranty, motorists should consider buying wheel and tyre insurance if they spend large amounts of time out on the roads.
To meet the above demands, tyres need to be manufactured to exacting standards: sometimes up to 200 separate raw materials are used in their manufacture. The difference between a cheap and expensive tyre is due to factors like the rubber compound being of a better quality, the amount of testing put into tread patterns and rubber stability and the fact that when making tyres at higher temperatures the tyres are of a better quality as a result.
The more testing done by a tyre manufacture the lower the road noise will be, the longer the tyre will perform at its peak rate and the safer your family will be. So it should not come as a surprise that there are many different types of tyres that are manufactured for our vehicles and that their treads actually do matter. Some of these are made for a specific purpose while others are purely used for high performance road driving, the race track, desert driving or more rugged terrain such as woodlands or farms.
Tyre Width and Tread
The tyre grip depends on its rubber compound and the grooves that are present in the tread pattern, as it is the tread that does all the work. The tread helps determine how well the tyre grips on a dry road. Each manufacturer designs its own tread pattern to achieve this.
In wet conditions, the tread grooves disperse road water, ensuring that the tyre stays in contact with the road and therefore grips the tarmac. If the tyre tread is not able to disperse enough water, then your vehicle will aquaplane. This is when there is no direct contact between the tyre and the road; the tyre loses grip and the driver looses control of the vehicle. The more efficiently the grooves expel the water, the better the tyre will be at maintaining grip in wet weather conditions. If tyre treads wear down, they have diminished ability to expel water and that is where it gets dangerous for you and other road users. Worn tyres are dangerous – do not drive on tyres with less than the legal tread limit.
There are many types of tread pattern, all of which are used for different performance issues including standing up to various driving forces such as cornering, steering and high speed braking, road noise reduction, low wear and traction with the surface you are driving on. Tyre treads are designed to cope with the road surface be it snow, farm tracks (large knobbly tyres for digging in), race tracks (soft tyres with minimal groves) or wet weather tyres (deep groves designed to expel water out and away from your car).
The sidewalls combine with the air in the tyre to carry the weight of the vehicle. The outside of the sidewall should always be where you find the tyre size and specification details. Damaged sidewalls could cause a blow out with deadly consequences.
There are legalities in relation to the tyre specifications. This is because they are the main safety features of a tyre. The manufacturer is responsible for any relevant sidewall markings and an owner is responsible for the condition of tyre including the width and tread depths.
The legal minimum tread depth for car tyres is 1.6mm continuously around the band of the central tread of the tyre, circling at least 75 % of the tyre. The remaining grooves must have a depth of a least 1 mm again circling 75 % of the tyre. It is always advisable to change the tyre before it gets to this level, not only for safety reasons, but legal reasons too. If you do not, and you are caught driving on illegal tyres you could be fined up to £2,500 per tyre in Britain, and could receive three penalty points too.
Belted/Radial Tyres
Today the radial or belted tyre has almost completely replaced the cross-ply tyre. The materials of the radial tyres inner casing runs perpendicular to the direction of tyre travel. If viewed side on, the materials run radially, hence their name. The only problem associated with the composition of this type of tyre is that the materials cannot absorb the lateral force when cornering or accelerating. To correct this, the materials are supported by another structural material, for example steel belts.
The steel belts are rubber encircled ropes of steel wire. They give structural rigidity and maintain the tread flat in contact with the road. With bead-wires, the ultra-strong steel wires hold an extreme resistance to stretching, therefore holding the tyre to the rim, even during very high performance driving.
Run Flat Tyres
Manufacturer have now developed tyres and systems that allow a vehicle to continue moving despite there being a loss of pressure in the tyres. Two systems are available. The reinforced tyre sidewall brands on the market include Bridgestone, Continental, Dunlop, Goodyear, and Pirelli. The other uses a rubber clip attached to the rim; brands using this system include Michelin. Car owners with a low tyre pressure warning system fitted need to be sure that their run-flat tyres can operate in conjunction with this. Although new cars will automatically be provided with the appropriate tyre choice, if car buyers are replacing run flat tyres with aftermarket upgrades, due care must be taken to ensure that they are compatible with your car.
Little Known Fact: Rubber car tyres actually deteriorate with age, this is even the case when those tyres have simply sat on a warehouse shelf and not been used. This aging means that the tyre will be more prone to sudden and unexpected structural failure. The same goes for your spare tyre which may have been in your vehicle’s boot for the past few years, or for those extra tyres stored in the garage! Never risk causing an accident just to save a little money. It’s false economy to buy tyres in bulk if you end up replacing them prematurely due to deterioration. Ask the retailer how long their tyres have been sitting on the shelf.
Summer Tyres
These particular tyres provide excellent driving and braking performance, both on dry and wet roads, during temperatures above freezing in the spring, summer, autumn and winter. Summer tyres typically perform well in warm weather and are not suitable for cold driving conditions. The simple block shaped tread on the tyre ensures that the tyre’s contact with the road is as firm as possible, giving maximum grip at all times.
Winter Tyres/Cold Weather Condition Tyres
These tyres are for use when the weather turns cold or there is snow and ice on the roads. The tread has a blocked design with deep, wide blades or grooves. The design of these tyres ensures that the increased performance in traction and braking necessary on winter road surfaces is achieved. The tread rubber gives excellent friction and allows flexibility at low temperatures. Most of the current designs are centred towards the braking performance and driving control on icy roads. Improvements in tyre design and technology have been made possible partly due to performance information gained from track motor sports.
All-Season Tyres
As their name suggests, these are designed for use all-year round, and are more complex than other tyres. This is because of the longer block-edge that is used for winter. More blades or grooves are apparent in these tyres to ensure improved braking and driving performance, produced by maximising the effect of its edge. All-season tyre tread designs provide superb all-around traction for various road conditions, whilst still providing even wear and low noise.
Snow tyres
Snow tyres are especially designed to perform better when driving in the snow. They have been designed to replace the standard tyre for the winter months to ensure driving on the snow and ice is safer. The type of rubber used maintains its elasticity, while deeper treads increase road traction. Higher volumes of snow, sleet and ice are displaced by using a tyre with deeper treads. They will perform well in such conditions as road flooding, ice and mud.
4WD Tyres
4wd tyres are produced for high performance on 4×4 vehicles, they will often be made for driving off-road too. Today many vehicles are built with four wheel drive capability; 4WD (4 wheel drive) is no longer the sole domain of Land Rover Discovery and Toyota Land Cruiser. Modern saloon cars like the Mitsubishi Evo and Subaru’s WRX also have four wheel drive systems which can be engaged either permanently or – as in the case of the Subaru Forester 4WD for example – can be engaged and disengaged as dictated by driving conditions. Gone are the days where 4WDs were only used by the military and emergency services. In fact as a group Future45 Ltd has found a steady increase in sales of gap insurance to buyers of 4WD Sports Utility Vehicles over the past 36 months and expect this market segment to continue it’s growth.
Little Known Fact: Heat can cause tyre fatigue resulting in catastrophic failure. The main causes of such failure are due to frequent overloading of the vehicle which overheats the tyres though friction; the other is simply by living in a country with a hot climate. Since the tyres are prone to failure far sooner in these conditions more frequent tyre condition checks should be made under these circumstances. Many tyre manufacturers recommend that a vehicle’s tyres are changed every 5 to 7 years on average even if they still have plenty of legal tread on them.
Car Tyre’s sidewall markings
Markings are apparent on all tyres; if your tyre doesn’t have any, then it is not an acceptable tyre. To choose the right type of tyre you should pay attention to what the information in these markings means. For example:
If your tyre has 175/65 R14 T imprinted on it then:
• 175 is the tyre width in mm
• 65 is the tyre sidewall profile or the sidewall height as a percentage of its width
• R means radial (rather than a cross ply)
• 14 is the diameter of the wheel rim, in inches
• T is the speed rating which must match, or exceed the maximum speed of your car.
Speed ratings are as follows:
S 180 km/h or 112 mph
T 190 km/h or 118 mph
U 200 km/h or 125 mph
H 210 km/h or 130 mph
V 240 km/h or 149 mph
W(ZR) 270 km/h or 168 mph
Y(ZR) 300 km/h or 186 mph
ZR Above 240 km/h or 149 mph
Big Brand Tyres & Their Reputations
It used to be the case that there were only 3 or 4 brands that were available, but due to mergers and the increasing demands and needs of the consumer, more budget brands have entered the marketplace. The main ones are:
Michelin(France) -This is the world’s number one tyre manufacturer. They own Michelin, BF Goodrich, Kleber, Uniroyal and Riken.
Bridgestone(Japan) -One of the top 3 manufacturers. Back in 2003 Bridgestone (Japan) recently announced that they would be investing heavily in new research and development to produce tyres in the high performance sector, and also intended to raise their stakes in Europe’s share of global Bridgestone business. This initiative was a success and has put Bridgestone firmly in amongst the worlds top tyre manufacturers. Today they own Bridgestone, Firestone, Daytona and Europa.
Goodyear Dunlop(USA) -Goodyear Chemical provides both standard and high-performance polymers, antioxidants, latex and adhesive resin products to its customers on a global scale. The business has annual revenues of more than $750 million. Recently merged to form one of the largest tyre manufacturers in the world, they own Dunlop, Goodyear, Fulda, Falken and Kelly.
Yokohama (Japan) -In the top 10 list of manufacturers. Their 4WD tyres are world renowned, Their name embossed on the tyre sidewall painted white ensures instant brand recognition.
Pirelli(Italy) -In the top 5 of manufacturers. Pirelli are one of the worlds premier premium tyre brands. High performance car and motorcycle tyres are synonymous with the Pirelli brand name. They have recently developed the Ceat and Courier brands.
Cooper Tyre(USA) -They own Cooper, Avon and Mastercraft.
Continental (Germany) -They own Continental, Uniroyal, General Tyre, Gislaved and Semperit.
Toyo (Japan) – They are one of the newest budget firms.
Kumho (Korea) – They are a budget range with an emphasis on sporting tyres.
Vredestein (Netherlands) – They have an enormously wide range of tyres and are constantly working on innovative solutions, which they prove in practice by regularly introducing new tyres.
Tyre Terms You May Have Heard Before
Rolling Resistance
The rolling resistance of your tyres can affect your fuel economy. Tyres should always be pumped to the correct pressure to maximise performance an duel economy. Therefore some tyres are described as “fuel savers”, “eco” or “energy” tyres. These tyres may have low rolling resistance. A general rule is that the narrower a tyre the more fuel you will save and they often, though not always, are less likely to aqua plane on road surface water at higher speeds! Interesting and completely logical when you think about it!
Tyre Pressures
Always check that your car has the correct tyre pressure. You will find the recommended pressure for your car either in the handbook, the glove box or the inside of the driver door panel. Check the tyre pressure every couple of weeks. Your tyres will warm up when you drive and the air inside them will expand, therefore for an accurate reading you need to check the pressure only when your tyres are cold.
It’s interesting to note how Formula One racing has employed this principle. Cold Formula One tyres are actually almost flat! They need to be brought up to temperature very quickly for optimal performance. Optimal performance is when the tyres are blisteringly hot and that makes them sticky as the rubber compound melts. This helps racing drivers by “sticking” the car to the track, especially when taking corners at high speeds. A Formula One car relies on the hot tyres as this expands the air in them, which in turn inflates the tyres. However in a road going car you must not drive with under or over inflated tyres as this will hinder the handling of the vehicle and their structural safety is also dependent on their inflation pressure. Uneven tyre pressure will increase both tyre wear and your fuel consumption.
Wheel Alignment
If you find that your tyres are evenly worn across the surfaces, this is a sign of good wheel alignment. If you find uneven wear on your tyres, it could mean that they are either over or under inflated. If your tyres are badly worn on one edge this could signal that the wheel alignment has been knocked off of track. It is then essential that you have your wheel checked by a reputable garage or wheel and tyre centre as soon as possible. They will check your wheel alignment, camber and toe settings for you to ensure a safer drive, lower fuel consumption and longer tyre life.
Wheel Balancing
Wheels are balanced using tiny leads weights placed on the outside of your rims after the tyre has been fitted to the wheel. Each wheel is done individually. If your wheels are unbalanced, not only will you feel a vibration in your steering wheel, but the vibrations become more violent as the balancing gets worse. These vibrations can cause mechanical damage to your car and the distraction to the driver is dangerous. Always seek professional help as soon as you feel that there is anything at all that may be wrong with your vehicle’s tyres. Not only your life, but those of your family and other motorists are also at stake. Again, it is essential that you have your checked by a reputable garage or wheel and tyre centre.
Spare Tyre
Always ensure that your spare wheel is in good condition. Check the spare tyre’s pressure and tread every few months, so avoiding any problems should you need to use it. Your spares tread should be within legal limits if you have elected to use a tyre which you previously had on your car. Best practice is to always have a brand new tyre for your spare. You can use either a full-sized spare, or buy a temporary “mini-spare” to save space. These are designed to take up less room in your vehicle and to get you home in an emergency. They are not meant to be driven on for long periods of time and they are usually not suitable for speeds in excess of forty to fifty miles per hour. If in doubt consult the manufacturer.
Directional Tyres
Directional Tyres guarantee the best possible sound reduction and water dispersion. For these reasons the tyres must be fitted correctly. Directional tyres are fitted with the arrow point and the words “ROTATION” pointing towards the forward driving direction of the vehicle.
Asymmetrical Tyres
Tyres with an asymmetrical tread also exist. These have a more open tread on the inner section and less open tread on the outer section. The less open tread is intended for high traction on a dry road and road adherence in corners while the inner section has a more open tread that results in an improved dispersion of water.
Tyre Care Reminder
It is essential that you maintain the tyre pressure, for safety, economy and for the sake of the environment. So check that all your tyres are at the correct pressures, every couple of weeks. Don’t forget to check your spare.
When you do this, also check for any tyre damage at the same time. You should have your tyres checked if you come across any unusual scrapes or lumps and bumps, as these could potentially cause tyre failure. Noticing uneven wear could mean that the wheel alignment is incorrect, or if you have braked suddenly, there may be a flat area. After any occasion when you have needed to apply your brakes heavily you should have your tyres professionally checked.
Remember that not only is it illegal to have tyres below the legal limit of 1.6mm, but you may well also void your car insurance. There will also be a greater risk of skidding and aquaplaning. Be sure to inspect the tread regularly.
This article was supplied by the Gap Insurance division at Future45 Ltd group of companies for informational purposes only and should not be construed as advice. In the interests of your safety please consult your local tyre replacement centre if you are in any doubt about the condition of your car tyres.