All about Tyres (and we mean all)

Tyre Law: Tyres must have a minimum depth of 1.6mm across 3/4 of the centre tread. The outside edges can be left with no tread. A fine of up to £2500 and 3 points can be given for each illegal tyre.

Click on a topic to learn more:

Overloading Alterations Fitting
Check Pressure Towing Repairs Mounting
High Speed Alignment Storing Tyres Speed Rated
Damage Rotation Snow Tyres  
Worn Out Mixing Spinning

Correct tyre pressure is very important. Driving on any tyre that does not have the correct inflation pressure is dangerous. Proper inflation pressure for your tyres may be found in the vehicle owner's manual or the vehicle's tyre information placard.

Any underinflated tyre builds up excessive heat that may result in sudden tyre destruction.

Refer to the tyre placard on the vehicle (check vehicle and/or vehicle owners manual for placard location) for the recommended operating pressures. These pressures must be maintained as a minimum. Do not exceed the maximum pressure indicated on the tyre sidewall of passenger car tyres.

If you are replacing the original size tyres with tyres of a different size, you must consult a knowledgeable dealer to determine the correct inflation pressure for your new tyres. If you need additional help, or still have questions, contact your Auto Technician for advice.

Check tyre inflation pressures (including the spare) at least once a month when tyres are cold and before long trips.

Failure to maintain correct inflation may cause rapid and irregular tyre wear, sudden tyre destruction and may result in loss of vehicle control and serious personal injury. Therefore, inflation pressures should be checked at least once a month and always prior to long distance trips. Any tyre is susceptible to losing air pressure if not properly maintained.

Pressures should be checked when tyres are cold; in other words, before they have been driven on. Driving, even for a short distance, causes tyres to heat up and air pressure to increase. Tyres run even short distances while severely under-inflated may be damaged beyond repair.

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High speed driving can be dangerous.

Correct inflation pressure is especially important. However, at high speeds, even with the correct inflation pressures, a road hazard is more difficult to avoid and if contact is made, has a greater chance of causing tyre damage than at a lower speed. Moreover, driving at high speed reduces the reaction time available to avoid accidents and bring your vehicle to a safe stop.

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Driving on a damaged tyre or wheel can be dangerous. Always look for bulges, cracks, cuts, splits, penetrations, and abnormal tread wear. Damage can occur within the tyre body without being visible on the outside. A vibration or ride disturbance may be a sign of tyre damage.

Any time you see any damage to your tyres or wheels, replace with spare at once and immediately see your tyre dealer to have the damaged tyre inspected.

If while driving, you notice a vibration or ride disturbance, and/or you suspect possible damage to the tyres or vehicle: immediately reduce your speed, drive with caution until you can safely pull off the road, stop, and inspect the tyres. If a tyre is damaged, deflate it, remove it from the vehicle, and replace the tyre and wheel with your spare. If you do not see any tyre damage and cannot otherwise determine the source of the vibration, have the vehicle towed to the nearest vehicle or tyre dealer for a thorough inspection.

These conditions may be caused by misalignment, underinflation, overloading, impact damage, and/or a separation within the tyre body. Use of a damaged tyre could result in sudden tyre destruction.

When inspecting your tyres, including the spare, check your air pressures. If your pressure check indicates that one of your tyres has lost pressure of two pounds or more, look for signs of penetrations, valve leakage, or wheel damage that may account for the air loss.

All tyres will wear out faster when subjected to high speeds as well as hard cornering, rapid starts, sudden stops, frequent driving on roads which are in poor condition, and off road use. Roads with holes, rocks or other objects can damage tires and cause misalignment of your vehicle. When you drive on such roads, drive on them carefully and slowly, and before driving at normal or highway speeds, examine your tyres for any damage, such as cuts or penetrations.

Worn out tyres are dangerous.

Tyres contain "Wear-Bars" in the grooves of the tyre tread which show up when only 1.6mm of tread remains. At this stage, your tyres must be replaced. Tyres worn beyond this stage are dangerous.

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Do not overload your tyres. Driving on any overloaded tyre is dangerous.

The maximum load rating of your tyres is marked on the tyre sidewall. Do not exceed these ratings. Tyres which are loaded beyond their maximum allowable loads for the particular application will build up excessive heat that may result in sudden tyre destruction.

Do not exceed the gross axle weight ratings for any axle on your vehicle. Consult the vehicle placard and/or vehicle owners manual to determine the gross axle weight rating. Following the loading instructions of the vehicle manufacturer should insure that your tyres are not overloaded.

If you are replacing the original size tyres with tyres of a different size, the replacement tyres must have a load carrying capacity equal to or greater than the original equipment tyres.

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Towing a trailer.

If you anticipate towing a trailer, you should see your tyre dealer for advice concerning the correct size of tyre and inflation pressures. Tyre size and air pressure depend upon the type and size of trailer and hitch utilized, but never exceed the maximum cold inflation pressure or the maximum tyre load rating. The only sure way to prevent overload is to weigh, axle by axle, the fully-loaded vehicle on a reliable platform scale. Check the tyre placard on the vehicle and the owners manual supplied by the manufacturer of your vehicle for further recommendations on trailer towing.

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Wheel alignment and balancing are important for safety and maximum mileage from your tyres.

Inspect your tyres regularly: at least once a month inspect your tyres closely for signs of uneven wear.

Uneven wear patterns may be caused by improper inflation pressure, misalignment, improper balance or suspension neglect. If not corrected, further tyre damage will occur. These conditions shorten the life of your tyres and may result in loss of vehicle control and serious personal injury.

If any of these conditions exist, the cause may often be corrected at your tyre dealer or other service facility. Your tyres will then last longer.

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Proper tyre rotation is important.

If you notice irregular or uneven tread wear, the tyres should be rotated to alleviate the problem. Remember: it is important to check your tyres and wheels for signs of possible damage (as previously discussed), and check your vehicle for any mechanical problems and correct if necessary. You should follow the rotation pattern or procedure indicated in your limited warranty and the vehicle owners manual. We recommend you rotate tyres on front wheel drive vehicles and/or all season tyres on any vehicle every 8,000 miles to equalize the rate of wear; however, rotate your tyres earlier if signs of irregular or uneven tyre wear arise, and have the vehicle checked by a qualified technician to determine the cause of the wear condition. The first rotation is the most important.

Sometimes front and rear tyres on a vehicle use different inflation pressures. After rotation, adjust individual tyre air pressure to the figures recommended by the vehicle manufacturer for the new locations - front or rear - as shown on the tyre placard on the vehicle.

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Tyre mixing can be dangerous.

Most passenger tyres today are radial tyres. For best performance, we recommend the same size and type of tyre be used on all four wheel positions unless the vehicle manufacturer specified different sizes, front and rear, as original equipment. Check the vehicle placard. If only two radials are mounted with two non-radials, the radials should be mounted on the rear. If tyres of different types are mixed on a vehicle in any configuration, they should not be used for long periods and speeds should be kept to a minimum.

Mixing or matching of tyres on four-wheel drive vehicles requires special precautions. Always check vehicle manufacturers' manual for their recommendations.

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Tyre alterations are dangerous.

Do not perform any alteration on your tyres. Alterations may prevent proper performance, leading to tyre damage, which can result in sudden tyre destruction. Tyres which have been altered are excluded from warranty coverage.

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For repairs, see any tyre dealer at once. Never use a plug-only or patch-only repair.

If any tyre has sustained a puncture, have the tyre dismounted and inspected internally by any tyre dealer for possible damage that may have occurred.

Punctures in the tread of passenger tyres which do not exceed 1/4-inch (6mm) in diameter can be repaired by following Rubber Manufacturers' Association (RMA) recommended repair procedures. A plug by itself or a patch by itself is an unacceptable repair. The repair material used - for example, a "combination patch and plug" repair - must seal the innerliner and fill the injury to be considered a permanent repair. Never use a tube in a tubeless tyre as a substitute for a proper repair.

If the tyre has a puncture in the tread which exceeds 1/4-inch (6mm), any puncture in the sidewall, or if more than one radial cable per casing ply is damaged, the tyre must be replaced.

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Use care when storing tyres.

When tyres are stored they should be stored in a cool, dry place away from sources of sunlight, heat and ozone such as hot pipes and electric motors. Tyres should be stored so there is no danger of water collecting inside them. Be sure that surfaces on which tyres are stored are clean and free from grease, gasoline or other substances which could deteriorate the rubber. Tyres exposed to these materials during storage or driving may be weakened and subject to sudden failure. Also, be sure to allow air to circulate around all sides of the tyres, including underneath, to prevent moisture damage.

When storing tyres flat (one on top of the other), stack so that tyres on the bottom retain their shape.

If storing tyres outdoors, protect them with an opaque waterproof covering and elevate them from the ground. Do not store tyres on black asphalt, other heat-absorbent surfaces, snow-covered ground or sand.

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Driving on studded snow tyres. If studded tyres are installed on the front of any vehicle, they must also be installed on the rear.

The beginning of movement and acceleration of any vehicle in snow, ice and other adverse cold weather conditions is highly dependent on the traction qualities of the tyres on the driving axle. The controlled handling and braking of a vehicle after it is in motion in adverse weather conditions, however, is highly dependent on the traction of the rear tyres. Consequently, the rear tyres of any vehicle must have equal or higher traction capabilities than the front tyres for safe vehicle operation.

Because of the higher traction qualities of studded snow tyres under most winter weather conditions, installation of only two studded snow tyres on the front of any vehicle (especially front wheel drive vehicles) without two studded snow tyres on the rear can cause adverse (unsafe) handling characteristics. Consult tyre manufacturer for correct stud size. If you sell and/or install studded snow tyres on vehicles you must follow the procedures listed below:

  • Only new tyres should be fitted with studs. Never insert studs in a used tyre (even if only slightly used).
  • Without studded snow tyres on the rear, which have the same traction qualities as the studded front tyres, adverse (unsafe) handling and braking characteristics are introduced into the vehicle. This may result in loss of vehicle control, which could cause serious injury or death.
  • If studded snow tyres are installed on only the rear of any vehicle, it is recommended (but not required) that they be installed on the front. Only if studded tyres are installed on all wheel positions of a vehicle will optimum handling characteristics be achieved

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Tyre spinning is dangerous. Excessive spinning can cause a tyre to "explode".

Avoid tyre spinning. The centrifugal forces created by a rapidly spinning tyre can cause an explosion by tearing the tyre apart. These forces act on the complete tyre structure, and can be of such magnitude as to break beads as well as rupturing the entire carcass.

When stuck on ice, snow, mud, or wet grass, etc., the vehicle should be rocked gently (alternately using forward and reverse gears) with the least amount of wheel spinning. DO NOT exceed 35 mph as indicated on the speedometer. Never allow anyone to stand near or directly ahead of or behind the spinning tyre.

Do not spin if a drive wheel is off the ground. Serious personal injury or death can result from the explosion of a spinning tyre.

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When replacing tyres and/or wheels, consult your Auto Technician to discuss safety precautions and instructions.

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Tyre mounting can be dangerous and should be done only by trained persons using proper tools and procedures.

Serious injury or death may result from explosion of tyre/rim assembly due to improper mounting. Always have your dealer mount your tyres on rims. If you are not thoroughly familiar with Rubber Manufacturers Association mounting procedures, never attempt to mount tyres.

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Speed-rated tyres. If the replacement tyre is not speed rated, the speed capability of the vehicle is limited by the speed capability of the replacement tyre.

When replacing tyres, consult the placard (normally located on a door frame, door edge, or glove box door) or the owner's manual for correct size. If the tyres shown on the vehicle placard do not have speed ratings, the appropriate size tyre with any speed rating may be applied.

When the placard tyre size contains a speed symbol, for example P205/60HR15 or P205/60R15 90H, the replacement tyre must have the same or higher speed rating symbol if the speed capability of the vehicle is to be maintained. If the replacement tyre is not speed rated, the speed capability of the vehicle is limited by the speed capability of the replacement tyre.

Speed       Category
*S          180 km/h (112 mph)
*T          190 km/h (118 mph)
*U          200 km/h (124 mph)
*H          210 km/h (130 mph)
*V          240 km/h (149 mph)
*W          270 km/h (168 mph)
*Y          300 km/h (186 mph)

* Based upon indoor wheel tests conducted in accordance with the Procedure for Load/Speed Performance Tests of the Economic Commission for Europe (ECE-30).

** For tyres having a maximum speed capability above 240km/h (149 mph), a "ZR" may appear in the size designation.


Tyre Designation        Maximum Speed
P275/40R17 93W          270 km/h (168 mph)
P275/40R17 93Y          300 km/h (186 mph)
P275/40ZR17 93W         270 km/h (168 mph)
P275/40ZR17 93Y         300 km/h (186 mph)

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