Rain

Rain and sleet can rob you of vision and make off with much of your car tyres’ grip. You can counter this in two ways. As regards vision, the tactic is simple – drive only as fast as conditions permit. If it’s teeming down and spray is lashing against your windscreen, just slow down.

As regards the degree of grip lost to rain by your car tyres, the solution is once again perfectly simple. Your stopping distance will increase on wet roads. So, you need to leave more space between your car and the car/van/lorry in front.

Unless standing water is rife, the amount of grip your car tyres have for cornering should be adequate. Slow down if you encounter standing water. At best it’ll tug your steering about; at worst your tyres will aquaplane. Riding on the surface of the water equals no grip.

Fog

Fog has no effect on the amount of grip your car tyres give but it has a marked effect on how far you can see. ‘Drive as fast as you can see, and no faster’ is sound advice but there are tricks that sort out the safe drivers from the statistics.

Fog can be unpredictable to say the least. Remember that just because you can see half a mile ahead in mist doesn’t mean that visibility can’t plummet in a sudden, thicker fog bank. If you find yourself hurtling towards the unforgiving tail of a lorry at terminal velocity, the best car tyres in the world won’t help. You’re driving far too fast for the conditions.

Don’t be caught out on the motorway, as once again, impeccable tyres won’t help. Big lorries punch a nice big holes in thick fog. You find this out when you pull out of a lorry’s slipstream to overtake. In what might appear to be a clear lane, you could be in deep trouble in a second. Use your windscreen wipers and washers regularly – fog is water vapour; it and grime build up surprisingly quickly. And use your fog lights, especially those at the rear.

Snow and Ice

‘Softly, softly catchee monkey’ is an old proverb, which happens to fit the best approach to driving on snow and ice. Getting the best from your car tyres on snow and ice demands patience and finesse, not to mention a lot of forethought.

Of course, we have helping hands nowadays. ABS means that even though you can skid through steering, you can also brake while skidding. Under less extreme circumstances, you might find you car’s behaviour hasn’t a great deal to do with your inputs at the steering wheel and pedals. Once again, it’s a matter of going too fast for the conditions.

What to do when your tyres’ grip is compromised? It’s wise to do nothing with the brakes and throttle. Use your steering instead. Say your car is ploughing straight on. It’s understeering and you can stop this by straightening the wheel until the grip comes back. Should the car’s tail end go wandering off, you’re in oversteer. Turn the steering in the direction the tail is heading. You’ll save it then but you may have to counter-steer in the opposite direction.

In bad conditions, ‘caution’ is your watchword. Grip and/or visibility will be compromised to some extent by bad weather. Should the visibility and grip be terrible, put your feet up by the fire. Then you will live to drive another day.

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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.

Luckily, car tyres are made to cope with harsh conditions, which they are perfectly capable of doing, with a little help from their friends, i.e. you, their owners. None of the following little maintenance tasks are particularly difficult, time-consuming or even expensive. Carry them out and your car – and its tyres will carry you around reliably, in most conditions.

The first idea to take on board is that there isn’t a road tyre made that will provide grip on sheet ice. On such a surface, a car tyre might as well be a ‘slick’ with no tread at all. However, on snow, slush and in the wet, tread matters. Officers of the law will have something to say if you don’t have the regulation 1.6 mm of tread around three quarters of all your tyres and this is a worst case scenario. In practice, letting tyres this worn meet winter conditions is folly.

How can you maximise grip? Among the car tyres on the market are numerous ‘Winter Tyres’. These are made of a softer than usual compound and offer superior grip in winter. But are they worth it? If you do a lot of driving in cold, disagreeable conditions, the answer is ‘yes’.

Then there are grip aids for car tyres. In some countries, snow chains are a legal requirement in winter conditions. This is not so in the UK but there are ‘snow socks’, tough, net covers that enhance grip in the short term at low speeds. Are these worth it? Assuming conditions are seriously bad, the answer is a qualified ‘yes’. Bear in mind that snow chains do tarmac a power of no good, while tarmac will soon put paid to snow socks. Think of these things as emergency equipment.

Naturally, car tyres should be at the correct pressure. Checking this is any easy job that should be repeated regularly throughout the winter. Bear in mind that temperature and tyre pressure are irrevocably interlinked, so head for the tyre inflation facility soon after the ice appears.

While up close and personal with them, run a hand over your tyres’ carcasses to check for bulges, lumps, cuts or the evidence of misalignment. Remember also that you have a spare tyre that you might need in a hurry. Check first that you can access it, particularly if it lives beneath the car. Finding out that the spare is shredded and corroded firmly into place mid-snow storm is undesirable at best.

There are a number of bits and pieces that warrant checking as much as car tyres. Screen wash fluid needs to be kept up to strength as well as up to level. The same goes for your car’s coolant, as well as its oil. A car battery rarely has to be checked these days but if yours is marginal, a cold snap will probably kill it off completely.

Your car tyres can’t carry you safely if you can’t see where you’re going. This is reason enough to regularly check every last bulb and LED on your car. Also, pensionable windscreen wipers merely tend to move snow and rain around on your screen. For deicing, a proprietary spray is worth having, as is the more paint friendly and economical

‘Ice Plane’. You can tackle frozen-up doors using cold water but be quick – it re-freezes. Hot or boiling water is a great way to crack cold glass. Remember that setting off peering through a ‘porthole’ that represents the total extent of your demisting is an offence.

Finally, what should you take on a winter journey? This depends on the conditions. For example, you might need a torch, reflective waistcoat or jacket and a warning triangle, and some extra screen wash fluid for normal journeys. Whether you need boots, gloves, a shovel and a thermos of tea depends on where you’re headed. The last, some bars of chocolate and heavy clothing are for when conditions are despicable. In any event, a functional, well-charged mobile phone can be a life saver.

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Buy the right tyres

Car tyre choice is a matter of making an educated selection. So-called ‘long-life’ tyres may perform as advertised but can have downsides. They are liable to be noisier in use than ‘normal’ tyres, whilst also being less grippy. Similarly, ‘normal’ tyres could save you a few pounds but could let a higher performance car down grip-wise. The solution? Trust your tyre fitter.

Make sure your wheels are properly aligned

Given that wheels running out of alignment spell an early demise for car tyres, it’s worth having a wheel alignment check at tyre replacement time. Significant misalignment will show in odd wear patterns on the tyre treads, and can make the steering feel odd.

If you’ve encountered a big pothole, road debris, or have had an argument with a kerb, get the alignment checked as a matter of course.

Use the right pressure

You can usually find this out from a sticker on your car’s doorpost, or from your user manual. Too little tyre pressure can cause fuel-wasting drag, excessive tyre flexing and tyre failure through overheating. Too much air in your tyres can lead to premature wear and unreliable handling.

Drive with sympathy

…,for your car tyres, that is. Consistently taking corners at 9/10^th of your car’s (or your) abilities shortens tyre life. The same goes for aggressive accelerating and braking. Movie stunt men don’t have to pay for their car tyres!

Give your tyres a break

Following on from the previous tip, this kind of mechanical sympathy specifically concerns physical damage to your car tyres. We have, for our pains, got to put up with speed bumps and speed pads on our highways. We don’t, however, have to let them damage our car’s wheels and tyres.

The way to tackle these devices is to treat them as what they are – hazardous to your car tyres. Always cross them slowly. If you come across the kind of speed restrictor where there’s one speed pad per carriageway, never straddle them. Instead, let the wheels on one side of your car traverse them. Also, try to avoid touching a kerb, far less mounting one.

Driving like this will protect your car tyres, as well as greatly reducing the chances of expensive and/or dangerous damage to wheels.

These are proven practices that will prolong the life of your car tyres. They can also help save wear and tear on your car’s wheels, suspension and steering. Don’t be misled by knowing that car tyres are very tough indeed. They are tough but they aren’t invincible. Pay attention to the above and stay safe, and you will save money by not having to replace your tyres before their useful life ends.

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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 you are, driving along, minding your own business. It’s pouring with rain but you’re perfectly confident about your car tyres’ abilities on wet tarmac. Then it happens, you’re faced with glossy sheen of floodwater in your path. Your thoughts begin to race. ‘Should I keep going, or turn round?’; ‘Will I get stuck?’; ‘How deep is it?’

Depth is the very first thing to consider in such a situation. In most instances, a car can handle floodwater as deep as its wheel rims – the car tyres will be submerged but they’ll cope. The snag is; how do you gauge the depth of the water?

There is no simple answer to this question. You may have local knowledge to tell you what to expect in a given location. You may have a good view of the white line, or you may have just seen another car successfully wading through the water. There are, however, warnings to consider. For example, you can bet your car tyres that a flood stretching away out of sight, such as around a blind bend, is liable to get deeper. Similarly, your seeing a big 4×4 happily paddling doesn’t mean your saloon car will manage.

Apart from your car tyres’ role, the major element to consider is your engine. All engines compress the fuel and air mixture that enters their cylinders. A petrol engine may squash the mixture by a factor of fourteen, while a Diesel engine might compress the mixture to twenty-five times atmospheric pressure.  Here’s the rub: you can compress air, you can compress vapourised fuel but you cannot – repeat cannot – compress water. A surprisingly small drink of floodwater will instantly stop whichever pistons encounter it. However, the connecting rods will still be pushed upwards by the crankshaft…but not for long. Broken or bent conrod(s) – for which read ‘scrap the engine’ are the inevitable result. This is exacerbated by many modern cars having a low-mounted air intake. Cool air drawn form low down equals improved combustion. Water drawn into the air intake equals a dead stop.

What, then, is in our line of defence before we try to dip our car tyres into floodwater? Local news, via the TV, radio or Internet, are helpful sources, provided you pay attention to them. It’s also a great idea to have a fully charged, functional mobile phone with you, just in case. Remember that, if you encounter a flood, asking around – especially if the police are present – could save your life, let alone your car.

Now for the worst-case scenario. You arrive at flood and have to decide on how to tackle it. Stop and take a look, getting out of your car unless you’re 100% sure of the water’s depth. Is the white line, or the underwater tarmac surface visible? If so, remember you can go to about the depth of your car tyres’ sidewalls in most cars. Is the water still? If it’s rushing, forget it – unless you fancy being on the news. Moreover, if someone starts beeping at you to hurry, invite him/her to go first. You’ll know what to do if this car suffers a grinding halt.

Assuming you plan to go for it, put your trust in your car tyres and go slowly forward. Use a low gear, so that the increased engine revolutions will allow the exhaust gases to keep the water at bay. Go slowly, so as to not create a big bow wave – which might just drown your engine. And remember to stick to the crown of the road, where the water will be shallowest.

Finally, though your car tyres will dry off after a few revolutions, your brakes will stay wet. Lightly touch the brake pedal until you feel the brakes bite again.

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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.

1. Wheel Alignment

When your car’s wheel alignment is correct, the tyres can run true on the road. This means that a balance exists between the car tyre’s drag and the amount of compliance in the car’s suspension.  Incorrect alignment spells increased wear, and can affect your rear wheels as well as the front ones.

2. Speed

Continuous high-speed driving accelerates car tyre wear. If you doubt this, just take a look at Formula One – pit stops aren’t to give the driver a rest while the tyres are changed!

3. Driving Style

If you drive sympathetically, your car tyres will last longer. Drive aggressively and you’ll pay for it through having to replace your car tyres sooner. An aggressive driving style will raise car tyre flexing and running temperature, and increase tread wear.

4. Car Tyre Placement

On a rear-wheel drive car, the front tyres must cope with steering and braking while the rear tyres offer traction as well as grip. On a front-wheel-drive car, the front tyres have still more to do, consequently wearing faster.

5. Vehicle Weight

Heavier vehicles wear our car tyres faster than lighter ones. There are, of course, heavier duty car tyres to compensate for this to some extent. However, the basic principle remains.

6. Car Tyre Type

Car tyres are constructed to meet particular needs. A performance tyre will give superior grip but will wear out sooner, as it has a softer rubber compound. Conversely, a harder, long life tyre will offer a longer life, at the cost of lesser grip and increased noise. There are tyre types that offer a compromise between the various demands on car tyres.

7. Tyre Pressure

An underinflated car tyre flexes more, runs hotter and wears faster than a correctly inflated one. Underinflation also increases fuel consumption, by creating additional tyre drag. Overinflation is nearly as bad, causing strange wear patterns and reducing grip.

8. The Passage of Time

This is the one aspect affecting tyre life that can’t be avoided. Ultra violet light causes rubber to degrade, as do chemical spills on the road. The usual giveaway is the appearance of cracked sidewalls…themselves indicative of a car tyre that is old. A car that is garaged will receive better car tyre life than a car that lives outside.

As is now clear, the factors affecting car tyre life – and performance – are many and varied. Mechanical sympathy and assiduous car maintenance positively affect tyre life. Conversely, it isn’t really surprising that bad habits can affect tyre life negatively.

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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.

To be attended to on a tyre machine, the car wheel with the tyre to be replaced must be taken off. Enter the trolley jack and powered wheel nut wrench. Almost without exception a key or adaptor to cope with the locking wheel nut is needed now. Soon enough, the errant car tyre will be detached from the car, complete with wheel.

Now the fun begins! We’re contemplating separating a big, tough rubber ring from the big, heavy metal wheel it’s been embracing, probably for many miles. The tyre fitter can unscrew the tyre valve and let the air out, but he can’t make any impression on the car tyre/wheel combination without mechanical assistance. This is why the tyre machine has powerful, compressed air-powered jaws, better known as the bead breaker. With the deflated car tyre placed correctly, all the fitter need do is press on a pedal. The jaws seize the tyre and separate the bead from the wheel rim.

The failed car tyre now has to go up in the world. More accurately, it has to lie flat on the tyre machine, with the wheel clamped firmly in place. More compressed air is used to let the machine seize the wheel firmly. Then, the fitter will place the hooked head of the tyre machine by the car tyre’s bead. Lifting the broken bead carefully over the wheel rim with a tyre lever, the fitter will flip it over the machine’s head. Another press of a pedal releases compressed air, causing the wheel to rotate. The tyre machine’s head peels the upper bead of the car tyre up and off the wheel rim. Repeat the process for the lower bead and that’s it – the old car tyre is off.

Now for a spot of wheel preparation. The old tyre valve’s inner fitting is sawn off and the valve is drawn out. The old balance weights will be peeled off or unclipped and, in some instances, the fitter will use a hand wire brush to clean corrosion off the wheel rim. Then, after having replaced the tyre valve, the fitter will apply a special compound to the wheel rim and the new car tyre. This stuff is a lubricant that will make fitting the new tyre easier.  However, where there has been an air leak between the old tyre and the wheel, the fitter will brush on a special sealant.

The tyre machine comes into play again now. Once cleaned, lubed (or sealed) and re-valved, the wheel is ready to accept the new car tyre. The machine is simply used in reverse order, the push the new tyre over the wheel rim, bead by bead. Using a compressed air line, the fitter will then inflate the new car tyre. Sometimes, the tyre/wheel will need encouragement to seal but the tyre will eventually seat itself   – sometimes with a loud bang – when air pressure builds up.  Throughout the car tyre-fitting process, the tyre machine has done most of the heavy work, while the tyre fitter carried out the intelligent tasks.

So, are we finished? Not quite – the wheel and car tyre combination need to be balanced. There’s another machine for this. Having placed the wheel on the tyre-balancing machine and clamped it on firmly, the fitter will close a safety guard and start the machine. The machine spins the wheel up to a given speed, which is usually about 200 revolutions per minute. Now it’s the balancing machine’s turn to be clever. Using its sensors and electronics, the machine will tell the fitter how heavy the balance weights need to be and exactly where they must go. Using the machine’s recommendations, wheel weights will be fitted and the newly balanced wheel taken up to speed again. Fine-tuning can be done but it’s rarely needed.

What used to be done manually, and could lead to sore hands and backache has been done quickly and efficiently. Should you watch from the comfort of the waiting area, you’ll know exactly what the fitter was doing at each stage of the tyre change…and why!

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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.

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.

It would be naïve to expect a set of car tyres to last indefinitely – they are consumables after all. However, bad driving habits, poor road conditions and mechanical faults can limit the lifespan of car tyres. Let’s look at some of the more common causes of premature tyre breakdown.

Much as your continuing health can depend on your car tyres, the health – and lifespan – of your car tyres largely depends on you. Yes, you can drive on the limit, squeaking your rubber on the Queen’s highway at every opportunity. Alternatively, you can drive more, well, let’s say soberly, and increase your car tyres’ longevity.

Though you can’t choose the road surfaces on which you drive, you can drive according to the road surface. We’re not quite at Third World status in this country but the combination of heavy traffic, severe winters and saving money on repairing the damage these do; means we encounter some bad roads. Car tyres are of necessity tough but they aren’t indestructible. When you find yourself driving on a particularly poor road surface, slow down. This gives your tyres an easier life and gives you time to steer round potholes.

There are also road ‘surfaces’ that can be detrimental to tyre life. Traffic-calming measures (some call them ‘traffic-harming measures’) such as speed bumps and speed pads can damage your car’s tyres, steering and suspension.

These devices are designed to make you slow down. The sad truth is that if they don’t do this sooner, they probably will later, to your cost. Rule one is to never straddle a speed bump. Your car tyres and suspension are not really designed to take a load that effectively pushes them outwards forcibly. Straddling speed bumps can lead to increased tyre and suspension wear, and misalignment. Instead, drive so that the wheels on one side of your car pass over the speed bump. Hint: if driving alone, let the passenger side wheels take the strain.

You can’t avoid full width speed bumps and speed pads, even for your car tyres’ sake. You could, of course, press on regardless but even big, butch 4x4s can suffer damage from excessive speed over speed bumps.

The other car tyre killer isn’t so much a road surface as a piece of street furniture. Kerbs have their rightful place in the scheme of things. Your car tyres have no right to be traversing or hitting kerbs. Yes, your car tyres have a cushioning effect, so you can lightly touch a kerb if it confirms your position during parking. However, with low-profile tyres and alloy wheels being so common, raked rims are all too evident. Look at a few parked cars and you’ll see the results of car wheel to kerb contact. Just bear this in mind: if the wheel rim is gouged, chipped or cracked, what’s going on in the tyre?

Such damage and the effect of speed bumps can put your car’s wheels out of alignment. This in turn causes the car tyres to wear unevenly, even if you don’t feel its effect at the steering wheel. Having wheel alignment checked isn’t too expensive, and is far less costly than new tyres. Have your car’s shock absorbers checked too, and remember that over- or underinflated car tyres cost, the latter in terms of fuel consumption as well as wear.

Looking after your car tyres and its suspension and steering pays dividends in terms of economy, longevity and performance. Should these not be enough of an incentive, there’s that small matter of personal safety too.

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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.

Efficiency Counts

The deductive powers of a Sherlock Holmes aren’t needed to figure out where car tyre factors could be costing us money. The key word is ‘efficiency’, and here’s how inefficiency can affect motoring costs.

All cars give a certain power output. Whether this is quoted in kilowatts, pferdestärke or good old horsepower is irrelevant, power can be wasted by inefficiency.  A certain amount of power is required to make a car progress, and anything that impedes this progression is wasteful. Under inflated car tyres require more power to make progress, because the lesser tyre pressure increases their rolling resistance. Run your car tyres at the correct pressure, or even a little higher, and you’ll soon see rewards at the fuel pump.

Of course, it isn’t just car tyres that can cause drag, which in turn increases fuel consumption. The current warm weather makes it tempting to use the car’s air conditioning. Would you use it so readily if you knew it could worsen your car’s fuel consumption by up to 11 per cent? You could open some windows, but this creates aerodynamic drag – it seems you can’t win. In fact, it makes sense to cool the car interior by opening the windows at slower speeds. When motoring at 40mph or over, use the aircon – it costs less.

Weight Issues

All car tyres create some drag, that’s also a fact. All car tyres also carry weight, and it’s a fact that the amount they carry can be trimmed, in some cases radically. What you carry on a regular basis in your car depends largely on how you use your car. That said, a lot of people carry unnecessary objects in the car at all times. You could argue that you really need your Wellington boots, snow shovel, overcoat and Thermos flask on board. Well, argue away – you’re carrying what represents dead weight for August and it’s you who are buying the fuel. A combination of ruthlessness and good sense about what lives in the car and when isn’t hard to apply.

Similar thinking should apply to your car’s roof rack or roof box. Sure, it’s well away from your car tyres but what’s on the roof costs you fuel simply by being their. Each has a weight, which you’re paying to transport. Each has a degree of air resistance, even if your roof box has sexy, aerodynamic styling. Again, you’re paying to push that roof-mounted deadweight through the air. Remove it when not in use and your pocket will thank you.

Obvious Strategies

There are a more fuel wasters than car tyre rolling resistance. Driving too hard and/or too fast when you needn’t are money guzzlers, as are speed camera fines and the increased insurance cost of points on your licence. Use the most efficient route, use the highest possible gear and above all, use your head. Everything in this article comes under a single heading, common sense.

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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.

Every car tyre has an area of tread, about the size of an adult’s footprint, in contact with the road surface. This is called, somewhat predictably, its contact patch.  Imagine the tyres’ four contact patches travelling along a road in a straight line. These four areas of tread are what keep your car on the road, allowing you to accelerate, steer and brake with confidence.

Now, what happens to car tyres in corners? Imagine the wheels following the arc that the corner represents. The wheels will be following the arc faithfully, but there’s a hidden force at work. Imagine you’re Superman and have X-ray vision. Looking down at the top of a wheel and tyre combination, you’d see that the contact patch will be following a tighter curve than the wheel is following.

So, what’s happening? Why the difference? It’s there because sideways force put on the tyre by the weight of the car is deforming the car tyre’s carcass. Now, imagine a straight line drawn through the centre of the wheel and another drawn through the centre of the contact patch. There will be a difference between the two – this difference is called the slip angle.

As slip angles increase, the car tyre’s grip increases, up to a point. When the forces involved head towards the maximum level of grip the car tyres offer, one of three states will apply. Say the slip angles are equal at both ends of the car. In this case, the grip at each end of the car will be the same. When the grip level’s limit is reached, the car will go into a classic, four-wheel drift. The car’s handling will be ‘neutral’. Racing cars are set up to give neutral handling.

Supposing the slip angles of the car tyres at the front are greater than those at the rear. Then, the driver will need to apply more steering input to make the car follow the chosen curve. This is called ‘understeer’.

When it reaches the limit of effective grip of its car tyres, an understeering car will slide off the track forwards – it simply won’t be able to corner tightly enough. In practice, most road cars understeer. Why? Because understeer is a generally controllable condition –  it’ll help scrub off excess speed when a corner is taken too enthusiastically.

The third state occurs when the rear car tyres’ slip angles are greater than those of the front tyres. The rear tyres will be giving less grip than the front ones. At the limit, the car’s tail will slide towards the outside of the curve. When you see a Formula One car or Touring Car spin off a track, it’s gone beyond oversteer.

This explanation is necessarily basic. In fact, very many parameters affect how car tyres respond to the forces imposed upon them. However, the physics are just as basic, and give car designers benchmarks from which to work.

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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.