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.

Suppose you were regularly wearing out a set of tyres on your Mini Cooper in three miles. You’d certainly be doing something very wrong, wouldn’t you?  However, this is the usual car tyre mileage on one of The Russ Swift Mini Display Team’s Coopers and Russ is doing something very right – in the eyes of his sponsors and spectators, that is.

The Team, part of Russ Swift Driving Services, was formed in 1981. Current British Autotest champion and England Autotest Team Captain Russ had often been asked to demonstrate his incredible, tyre-testing car control skills. He realised a gap existed in the marketplace and contrived to fill it.

In 1987, an advertising agency saw a video of Russ at work. This led to the renowned Montego “Car Park” commercial. Though this was aired in the UK for just six weeks, the squeal of tortured car tyres was heard when the performance was featured at the Cannes Film Festival. It was also voted by American judges as the world’s most imaginative car commercial.

Where did Russ go from there? A long, long way. Eight thousand tyre-munching displays in more than 50 countries and three Guinness world records (Parallel parking in the tightest space, J Turn in the tightest space and the fastest donuts) form just a small part of his CV.

Russ and Minis go back a long way too, starting with four British Autotest Championship wins and an International Rally win in Sweden in the early eighties, in a Cooper S. More recently, Russ was involved in promoting the remake of ‘The Italian Job’, performing at premieres in London and New York. He fulfils an advisory role with many police, military, royal and diplomatic drivers, also working closely with RoSPA, the IAM and various other road safety bodies to promote safe driving. A versatile player on the car world’s stage, Russ is committed to ensuring that it is only car tyres that suffer!

The tools of Russ’s trade are largely unmodified cars. Russ uses a Mini Cooper S, standard apart from a “piece of tape on the handbrake button”. Another Mini Cooper has one other mod – a locked differential – to allow for driving on two wheels (this is the one that gets 3 miles per set of tyres – should that be per pair?). Typically, a further Mini Cooper is used (all these are BMW MINIs). Often, an MR RS Mitsubishi Evolution undertakes power slides and donuts.

A typical show features reverse spins at 40mph, parking in a slot between two cars parked side by side, using only the handbrake. Similarly, ‘parallel parking’ involves a handbrake turn into the gap between two cars parked as though at the kerbside. Then there is a ‘dance routine’ to music, involving two cars and a ramp. This last – the ramp – is used for the business of getting the locked-diff Cooper up on two tyres. The show features music and commentary – and audience participation is encouraged. The tyres may be red hot but the invited passengers have been known to end up on the pale side!

Find out more – and see pictures and videos – at www.russswift.co.uk.

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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.

On petrol cars, a catalytic convertor has become a standard part of the car exhaust. Catalytic convertors – ‘cats’ for short – originated in America. Like many other items, cats soon went transatlantic and later made their way into European legislation. Unsurprisingly, they wound up in the UK.

Let’s begin with the nuts and bolts of the matter. In chemistry, a ‘catalyst’ is a substance that causes or accelerates a chemical reaction without itself being affected. Fair enough but what has this to do with car exhausts? Still talking at nuts-and-bolts level, a catalytic converter is a device that uses a catalyst to convert three harmful compounds in car exhaust gases into harmless chemicals.

Again, fair enough but what are these three compounds that are so harmful? They are to be found in the exhaust  gas of any petrol car and consist of…

Hydrocarbons (incompletely burnt fuel)

Carbon Monoxide (formed when petrol burns)

Nitrogen Oxides (made by combustion heat making atmospheric nitrogen combine with oxygen.)

So, just how scary are these components in car exhaust gases? Carbon Monoxide, a.k.a. CO, is the nastiest one, being poisonous to any organism that breathes air. Nitrogen oxides (NO2) lead to the formation of both smog and acid rain. Relatively innocent Hydrocarbons (HC) just produce smog but are particulate matter, which makes matters worse.

A catalytic convertor, looking rather like a silencer, forms part of a car exhaust system. The catalyst used is liable to consist of precious metals such as rhodium, platinum and palladium. These coat a ceramic honeycomb or ceramic beads inside the ‘cat’. Carbon monoxide is converted into the less harmful carbon dioxide (CO2) and hydrocarbons are converted into carbon dioxide (CO2) and water (H2O). As for the nitrogen oxides, these are converted back into nitrogen and oxygen.

Though they don’t have moving parts, ‘cats’ can suffer malfunctions. If the catalytic convertor in a car exhaust stops working, you won’t necessarily know about this until your next MOT test. A failed cat may just be worn out or its substrate (the metal-coated pellets or ceramic honeycomb inside) may have broken down. Your car may run perfectly well – it just won’t be able to pass the emissions test part of an MOT.

Often, diagnosing what’s awry with the cat in a car exhaust is tricky. If something has gone wrong with the car’s fuel system and it allows raw fuel into the cat, the unit will run red hot. This is usually pretty easy to detect, which is just as well, as the substrate can shatter at such temperatures. Fouled sparking plugs, incorrect ignition timing and failure of the engine’s air pump and/or check valve can also cause overfuelling.

Should the cat’s innards go into meltdown, or shatter through thermal shock or overheating, the result will mimic a blocked car exhaust. A sluggish throttle response is the major clue. Modern electronics mean that a fault light will flash to verify there’s a problem but detecting exactly what the problem is likely to involve diagnostics – on a laptop computer. In any event, should the problem lie within the ‘cat’, a good tyre and exhaust bay will be able to offer you a replacement unit.

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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.

Formula One teams spend vast amounts on research and development. They spend on aerodynamics, on construction with composite materials, and on wringing the maximum amount of power from their engines. We must, however, remember that in Formula One, tyres remain the largest single performance variable.

So, car tyres are car tyres, right? Not quite; road car and racing car tyres are distant relatives at best. Road car tyres are made to last, typically for a life of 16,000 kilometres or more. Formula One car tyres are made to last 200 kilometres at most, but they are made to be both light and strong. Their internal nylon and polyester structure, with its complicated weave pattern, is designed to handle much greater forces than a road car tyre faces. Let’s put it this way, no road car is likely to generate a tonne of downforce, or 5g of longitudinal load…or 4g lateral loadings.

F1 car tyres’ soft rubber mix is there to offer maximum grip, at the cost of a limited life. The tyres wear very quickly. They also become very hot but this is meant to happen – cold race tyres offer little grip. By way of example, the dry grooved tyres used until recently were designed to run at between 90 and 100 degrees Centigrade. Look carefully at the TV footage and you’ll see the cars’ tyres, pre-race, clad in special coverings, which are electrically heated. The need for heat explains why Formula One cars can be seen weaving from side to side on the way to the starting grid. The drivers are perfectly sober and they aren’t playing – they’re just warming their tyres.

Slick tyres, those with no tread at all, offer maximum grip. However, it was decided in 1998 that slicks be outlawed. Grooved tyres were made de rigeur, to help improve F1 racing as a spectator sport by reducing cornering speeds. This made life difficult for the tyre makers. The rules specified that all tyres had to have four continuous grooves at least 2.5 millimetres deep, spaced 50 millimetres apart. So, tyre manufacturers had to adopt harder rubber compounds, to maintain tyre integrity. By the 2009 season, slick tyres came back. The FIA, Formula One’s governing body, decided to use limits on F1 car aerodynamics as a means of keeping cornering speeds down.

How ‘soft’ or ‘hard’ the rubber compounds in F1 car tyres are, is varied by race, according to each track’s characteristics. For each Grand Prix race weekend, teams choose from two different compounds, and every driver must use both during the race. What makes the difference in the hardness of the different specifications? A change in the proportions of ingredients added to the rubber mix. Of these ingredients, the three main ones are sulphur, carbon and oil. In general, more oil equals a softer tyre compound.

Formula One car tyres are obviously run at the appropriate pressures. However, air pressure isn’t quite the right term. F1 car tyres are inflated with more nitrogen gas than air. This gas and air mixture is less susceptible to pressure loss and minimises the pressure differences that come about through temperature changes.

As will have become clear by now, there are huge differences between road car tyres and Formula One car tyres. They may share basic characteristics but the common denominators between them are certainly low on the scale.

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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.

‘Blowout’. It’s a funny word. Unarguably a noun, it means…

1a.  A sudden rupture or bursting, as of car tyre.

1b.  The hole made by such a rupture.

2.  A sudden escape of a confined gas or liquid, as from a well.

3. Slang A large party or other social affair.

4. Informal A lopsided victory or thorough defeat.

Here, we are concerned with part 1a of the definition. Blowouts are less common than they used to be but the usual suspects cause them. These are under inflation, overloading, impact damage, structural damage or a big puncture.

You’ll notice that these factors have one thing in common. All cause or lead to a sudden loss of air pressure in the car tyre. The common denominator in any blowout is that it happens suddenly. The cause matters in that by taking care of your tyres means you can often avoid the risk of a blowout. Here, ‘taking care’ means keeping your tyres correctly inflated, and inspecting them frequently to look for cuts, bulges and other significant damage. Remember that a careful inspection should follow any known or suspected impact, such as with a kerb, road debris or a pothole.

Should the worst happen and one of your car tyres deflates quickly, your response can make the difference between a safe, controlled stop and a one-way trip into a ditch or worse.

Picture the scene. You’re driving along, minding your own business. Suddenly, you hear a tyre letting go. BANG…hiss…flap…flap…flap! Your natural reaction will probably be to hit the brakes and try to wrestle with the steering wheel, which will be suddenly pulling to one side. WRONG!…and it makes no difference whether your driving a sports coupe or a big luxury car. Your natural reaction is…well, natural but it can be very dangerous.

The trick is to first of all follow the well-known advice of Corporal Jones in ‘Dad’s Army’. Instead of panicking, briefly dab the accelerator, or at least don’t lift off it. Maintaining the car’s momentum will let you keep in the lane in which you were travelling when the blowout happened. You’ll have to apply counter steering to fight the car’s natural tendency to veer off line but you’ll find that you can still follow a reasonably straight track and keep the car stable. Then, gently ease off the accelerator and let the car slow down gently.

At this point, it’s a great idea to activate your car’s hazard lights. Your car should still be under control but you’ll have to stop pretty soon and the hazards will tell other drivers that not all is well. Ignore the noise and debris emanating from your wrecked car tyre. You can then pull over to the side of the road as soon as you find a safe place to stop. Under the circumstances, it’s OK to drive on for a short distance; the failed car tyre will be history anyway.

Finally, it’s no good heaving a sigh of relief at having survived a blowout, only to be killed by a passing truck while trying to replace the wrecked car tyre. Never attempt to change a tyre on a busy road. Call out your breakdown provider if you can’t reach a safe, quiet place to fit the spare wheel.

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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.

According to research carried out in May 2011 it’s official. What’s official? That we don’t all maintain our car tyres properly and this is proving costly in more ways than one. For their study, statisticians checked out 2,700 car tyres across the UK and uncovered some disturbing statistics.

The study showed that more than two thirds of cars in the UK are being driven with tyre pressures at least 3 psi below the manufacturer’s recommendation. According the study, the average amount of under inflation is 5.75psi, a staggering 18 per cent below the recommended figure. It is estimated that UK motorists are wasting £993 million on additional fuel to compensate for the drag caused by under inflated car tyres. Under inflation can also cause poor braking and handling, and can lead to tread damage and even blowouts. The study also found that nearly ten per cent of cars had a difference of  10 psi or more between tyres on the the same axle. If you’ve ever driven a car with such a prssure mismatch, you’ll know how unstable it felt.

Over inflation of car tyres also reared its ugly head. The study revealed that one in seven cars are tottering around with at least one tyre that has 3 psi or more pressure in it than the manufacturer recommends. This can quickly cause irregular tread wear and may lead to bulging of the tyre’s sidewalls.

The car tyre that’s usually out of sight and therefore out of mind was also found to be lacking, specifically in terms of air pressure. On average, the spare tyre was under inflated by a whopping 18 psi, 44 per cent lower than the recommended average pressure of 44 psi. So, many a driver needing to use the spare tyre could be in for a nasty shock. Fitting the spare wheel and carrying on regardless on a soft tyre may not be grounds for an immediate accident but it remains potentially disastrous.  It’s worth noting that space saver spare tyres generally have to be inflated to a much higher pressure. This, probably up to 60 psi, is almost twice the pressure used in a conventional car tyre.

Should a car tyre prove incapable of holding its pressure, this could be down to a puncture or slow leak at the valve. Such problems are usually cheaply and easily fixed at a good tyre bay. For those concerned about the pressure in their spare tyre, there’s the option of having it inflated with nitrogen. The molecules in nitrogen are both bigger and drier than those in normal compressed air, so the tyre will maintain its correct pressure for longer.

So, in among these sobering statistics, is there an encouraging figure? In short, is anybody getting it right? There is but it hardly makes for any degree of self-congratulation. According to the study, there are motorists driving around with all four car tyres inflated to the recommended pressure. However, haloes are thin on the ground…only four per cent of the motorists surveyed could boast that they were travelling on correctly inflated tyres.

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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.

There are a great many movie star cars but some are rather less well known than others. All have put tyres to tarmac on screen and many still do off screen. Here are three star cars that perhaps aren’t quite as familiar as some of their competitors.

Our first contender is the car that never was, in production terms at least. The Toyota 2000GT attracted a lot of attention when it first appeared in 1967. At the time, Japanese motor manufacturers were known for producing practical (i.e. boring) and derivative models. When ‘Road and Track’ magazine tested the 2000GT, it was described as, “One of the most exciting and enjoyable cars we’ve driven.” It was also favourably compared with Porsche’s 911. So, where have you seen a Toyota 2000GT on screen, spinning its tyres as competently as all the rest? You saw one in ‘You Only Live Twice’. This white convertible was driven by James Bond’s girlfriend Aki (Akiko Wakabayashi), with Sean Connery in the passenger seat. Why was it the car that never was? The Toyota 2000GT was a coupe that was too low for the 6ft 2 in tall Connery to fit into comfortably. Yamaha – who built the car – tried making a targa-top version but Bond’s head still protruded far above the windscreen, giving a rather ridiculous look. So, just two ‘convertibles’ were built especially for the film. Look very closely and you’ll see that the car’s folded ‘hood’ is nothing more than an upholstered hump.

Sticking with Bond film trickery, can a car really become a submarine? In 1977, ‘The Spy Who Loved Me’ would have had us believe one could. The Lotus Esprit S1 concerned tucked its tyres into its wheel arches (which magically filled themselves in), sprouted hydroplanes and apparently went diving. In reality, there was a real roadgoing Lotus Esprit S1, and a heavily modified body shell for underwater use. This shell was fired off a jetty using a compressed air cannon. The underwater mock-up was able to drop ‘depth charges’ but it had no real submarine abilities and no engine. Perhaps appropriate in a movie in which the villain was named ‘Stromberg’ – also the name of a kind of carburettor!

In the same year, ‘The Car’ was burning tyres and rendering audiences awestruck. The possessed star car in this average schlock-horror shocker (also known as DeathMobile) was based on a 1970-ish Lincoln Continental Mk III. In fact, four cars were built, two being destroyed during filming. The main stunt car featured a 460 cubic inch V8 engine, a roll over bar, heavy-duty suspension and amber-tinted glass. A locked 4.11 to 1 differential allowed for easier tyre spinning. The fourth and last car was based on a late 1970s Ford Thunderbird. It was loosely assembled, to be shot over a cliff for the final scene. The shop behind all this heavy metal was Barris Kustoms in North Hollywood. Barris was also responsible for building the original Batmobile, The Munster’s Koach and the Green Hornet car, ‘Black Beauty’.  The 1977 invoice for ‘The Car’ shows it cost ‘$84,000.’

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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.