Merityre Article Archive

Car tyres? Pretty much of a muchness, aren’t they? The one-word answer is ‘no’. There are many different kinds of tyre and here are six types used with road cars.

The most commonly-fitted type of car tyre is known as a standard, or all-season tyre. Such tyres are essentially a compromise. They work well enough in both wet and dry conditions, last for a fairly long time and aren’t too noisy on normal road surfaces. A jack of all trades and therefore a master of none? You may think so but in practice, standard car tyres work well for a lot of customers. There are some sub-divisions within this classification. Some car tyres are claimed to give better fuel economy, for example. These nevertheless remain under the ‘standard tyre’ banner.

So, when might you need non-standard tyres? Winter is a good example. Winter tyres come into their own when there’s snow and ice to be tackled. These car tyres have coarse tread patterns, the better to keep the treads clear of snow and ice. Less obviously, they contain rubber compounds and structures that remain flexible at lower temperatures, which enhances performance and roadholding. On the downside, they are noisy and, in normal conditions, wear out faster than standard tyres. For this reason, some people have a set of winter wheels to go with their winter tyres.

A car tyre that performs well in cold weather is totally different from a performance tyre. These, sometimes called ‘summer tyres’, are made of softer compounds, to offer superior grip. As well as having impressive marked speed ratings, such car tyres can cope with the demands of more powerful, faster cars. To do this, they trade wear rate for performance – they don’t last as long as lesser rubberware, and they abhor cold conditions.

As their name implies, run-flat tyres can be used even after suffering a puncture. Such car tyres achieve this with the imposition of a specific distance and speed up to which they can safely be used. Space-saver tyres are a cousin of run-flat tyres. The take up less space in the car but when fitted, must be used with similar restrictions on speed and distance.

What about the still less friendly conditions we might encounter? Enter the all-terrain tyre. For use on such surfaces as gravel and sand, these are particularly tough customers with very bold tread patterns. They have stiffer sidewalls, and the kind of structure that can handle potholes and debris on the road. The car tyre for all seasons? Not really. Sturdy? Yes. Long-lived? Yes? Quiet? Definitely not!

Similarly, mud tyres have an extremely large tread block pattern and are suitable for use only in muddy conditions. Car tyres of this kind are often used on those four-wheel drive vehicles that are actually taken on rough roads; this includes 4×4s that specifically go off-road regularly. The ‘Chelsea Tractor’ that does the school run doesn’t need them.

As should be obvious, the type of tyres you choose depends entirely on the use to which they will be put. Your local Merityre staff will happily give you a professional opinion on what type will be best for your needs.

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Merityre.co.uk are one of the  leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Car tyre forensics seems like an odd concept. However, in many instances, a ‘dead’ tyre can give you as much information as a corpse in the hands of a police pathologist. Information? Yes, tell-tale signs that can tell you what caused the tyre’s untimely demise. Such information is useful because in indicating possible faults, it can tell you what might require fixing to give your replacement car tyres or tyre the maximum possible life.

Let’s start with the basics. The type of tyre wear pattern that’s to be expected is straightforward, and is characterised by the tread’s having been worn away to the extent that the tyres’ tread wear indicators are at or near level with the surface of the tread. So, the tyre has nearly finished its useful service life. Is this the end of the story? Not necessarily. The suspension geometry on some cars can mean that the tyres’ treads don’t necessarily wear completely evenly.

Other car tyre tread wear patterns tell a different tale. What must be borne in mind is that they don’t necessarily tell it quickly – some wear conditions take a while to show that something is awry. For example, what does feathering on both outer edges of the tyre tread suggest? This pattern is the most likely indicator that the tyre has been consistently run at too low a pressure. Conversely, a strip worn around the centre of the tread indicates a tyre having been run at too high a pressure.

What about feathering on one edge of the car tyre tread? Should such wear be on the outer edge of the tyre, it suggests that the car’s steering is misaligned, having too much toe-in. Similarly, feathering on the tread’s inner edge indicates that there is too much toe-out. This kind of wear usually appears on both front tyres, as the steering will generally attempt to run straight and true. The fact that the steering tries to compensate for misalignment by effectively evening out the wear on each side of the car is no compensation in itself. However, it does advise you to have the wheel alignment checked before your new tyres suffer.

It’s worth noting that feathering on one side of a car tyre tread occurring only on one side of the car indicates something other than misaligned wheels. In this instance, one-sided feathering is more suggestive of wear in the car’s suspension joints, its springs and/or its wheel bearings. This pattern can also occur when the wheel’s camber, its position in relation to the vertical plane, is incorrect. Camber change of this kind can be caused by wear in the aforementioned areas; damage to the suspension can cause the same problem.

‘Cupping’ is also a phenomenon that can show you something is amiss on your car. A tread with cupping (also called ‘dipping’ or ‘scalloping’) has patches of wear across its tread’s surface. This can look almost like the tread surface has softened in places, or has been scooped away. Cupping indicates one of two problems or a combination of them. Wheels significantly out of balance can suffer cupping, as can car tyres under the control of worn shock absorbers. Cupping can affect rear tyres but it’s more commonly seen on a car’s front tyres.

As you can see, car tyre tread wear can be the result of maladjustment but wear and damage can give similar results. In the interests of your wallet, if not your life, pay attention to what your car tyres are telling you.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Here’s a sobering thought. Summer or winter, rain or shine, all that lies between you and a short, damaging trip into the scenery is the equivalent of the area of four shoe soles. Yes, every car tyre has a ‘contact patch’ the amount of its treaded area that touches the road. This area is only the size of an adult’s footprint.

Let’s say your car weighs one tonne. Nobody weighs half a tonne and the soles of his or her shoes do a pretty good job, expect perhaps on ice or snow. Translated into car tyre terms, the four-sole area has to do much, much more. It’s unlikely, for example, that a road car could generate a cornering force of 1g. Under heavy braking, it’s quite possible for such a force to be generated. Moreover, the forces generated during acceleration and cornering can be very high. Your car tyres and their contact patches do more than a ‘pretty good job’. You don’t usually expect your shoes to keep you from slipping in adverse conditions, such as on gritty or diesel-soaked tarmac in extremes of temperature. Your car tyres do this on a regular basis.

Legally, each of your car tyres must have a minimum of 1.6 millimetres of tread across ¾ of the width of the tyre’s running surface. Not meeting this requirement can get you three penalty points on your licence, as well as a £2,500 fine…per tyre. So, four balding car tyres equals a lost licence and fines of up to £10,000.

In this context, the law could be called an ass. Why? Because just 1.6 millimetres of tread on a car tyre is cutting things fine when it comes to grip. The Royal Society for the Prevention of Accidents (RoSpa) put this to the test. They tried some emergency stops in a typical car on some typical surfaces. On smooth concrete, as some motorway stretches have, the car’s barely legal tyres took a distance of 46.6 percent more to stop than an equivalent car with good tyres. Similarly, on hot rolled asphalt, the worn tyres needed 36.8 percent more distance to bring the car to a halt. There’s no need to ask why RoSpa recommends a minimum tread depth of 3 millimetres.

This isn’t the only scenario where worn car tyres will struggle. Tyres are designed to act like water pumps in wet conditions, they can clear surface water from their contact patches. When this fails to happen properly, the tyre will ride on a thin film of water. If this happens, you’d feel the steering lighten, which is an indicator of what’s actually going on. When a car tyre is unable to cut through road water fast enough, it will aquaplane. Aquaplaning equals significantly reduced grip, as you might find out when you attempt to steer or brake.

Whilst it may seem to make sense to get the very most out of the treads on your car tyres, there is such a thing as false economy. Your car tyres have wear indicators, moulded into the treads. Take a look at them and, if the treads no longer stand proud of the tread wear indicators, it’s new tyre time. Running your tyres down to the legal minimum could cost you far more than you think.

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Merityre.co.uk are one of the  leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.

Last night’s frost warning was a harbinger of the approach of winter. Here in the UK, we should be used to harsh conditions. However, give us an inch (of snow) and the miles aren’t covered…the country tends to come to a grinding halt. Is there a solution? Well, the increasingly popular winter car tyres may help.

This begs a question: are winter tyres genuinely useful or are they just a way of extracting more money from we motorists? Let’s see.

Recommended in Andorra, Italy, Norway and Switzerland, winter tyres are compulsory in Austria, Germany and Sweden and mandatory in Finland. These rules naturally apply on snow-covered roads and/or during the snow season. Often, there is the distinction that the tyres must be marked ‘M&S’ (no, not Marks and Spencer, the marking stands for ‘Mud and Snow’.) Newer snow tyres may have a symbol of a snowflake in front of a mountain. Currently, the distinction between winter and snow tyres is a touch unclear. A good tyre bay will advise you of the exact designation and specification.

In fact, specification is what winter tyres are all about. Car tyres in general are made in much the same way but the rubber compounds used and the tread patterns vary. Winter tyres are made with a high silica content. The probable tread pattern has two tricks up its sleeve. One is a more aggressive tread pattern than ‘summer’ car tyres. This is present to enhance grip.

The winter car tyre tread’s second line of defence involves a winter tyre key word, flexibility. When ordinary tyres have to work in temperatures below 7 degrees centigrade, they stiffen up in the cold conditions. In winter tyres, the compound and tread pattern both improve flexibility.

The benefit of winter tyres is that they give better grip in cold conditions, in rain as well as when snow and ice are about. There are plenty of subjective reports concerning car tyres and most of those concerning winter tyres are favourable. In some cases, cars found to be pretty hopeless in snow are transformed!

Are winter tyres the car tyres for all seasons? Their name offers a huge clue here. Summer tyres will outperform winter ones on dry roads and in reasonable temperatures, and winter tyres, having a softer compound, will naturally wear faster. This suggests following the lead of many continental drivers. They have two sets of tyres, one for winter, one for summer.

This brings us, in turn, to a potentially superior arrangement, which is also popular on the continent and in some cases is a legal requirement. Generally speaking, car tyres can handle most road conditions. However, in the depths of winter, the environment down at road level can be especially harsh. Car tyres may be able to cope with the salt and grit that gives some winter grip but our alloy wheels can suffer. Many popular cars have base models that wear steel wheels. One solution is to have a set of winter tyres on these. A set of steel wheels, with winter tyres, balanced and ready to roll can be fitted when the thermometer starts to plummet. With these ‘winter wheels’ fitted, your car can take on whatever the season has to throw at it, while your pristine summer wheels can live in cool, dark storage, ready for Spring. Bear in mind that suitable wheel nuts/bolts will have to be factored into the equation.

What’s the bottom line? Assuming you need to use your car in the off season, winter car tyres are worth the investment.

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Merityre.co.uk are one of the leading UK independent suppliers of car tyres. Why not visit their website for an online tyre quote or contact your nearest fitting centre.