For example a tire size of 205/55R16 indicates it has a section width of 205mm (nominal), 55 an aspect ratio of 55% (ratio of tire sidewall height to section width H/S) and 16 the rim diameter in inches the tire can be fitted.
Following the tire size information is the service description e.g. 91V indicates a load index of 91, by referring to the load index table shows a maximum carrying capacity of the tire of 615kgs and V a maximum speed of 240km/h (150mph).
The tire age can also be found by examining the characters following the symbol "DOT". The last four numbers identify the date of manufacture of the tire to the nearest week. The first two of these four numbers identify the week of manufacture (which range from "01" to "53"). The last two numbers identify the year of manufacture (e.g., a tire with the information "DOT XXXX XXX 3112” was manufactured in the 31th week of 2012).
Tires can become damaged without the driver’s knowledge. Most common damages are punctures, cuts, impacts, cracks, bulges and irregular wear.
If you do discover or suspect damage, have the tire inspected without delay by a tire service professional.
Continental recommend:
If you have to drive over an obstacle (e.g. curbstone), approach it slowly – as close to the perpendicular as possible. Check your tires regularly for exterior damage such as cuts, cracks or bulges.
There are several types of irregular wear. Most typical ones are heel and toe wear, one side wear, center wear, braking flat spots. For all of them, there are different reasons how this kind of wear occurs.
“Saw-tooth” wear is a wear pattern caused under normal usage with normal suspension settings. This is the outwardly visible (and audible) manifestation of various distortional forces at work on the tread. To explain this, it is better to first say something about ”tread design”.
Tread grooves and sipes – a source of noise – are absolutely essential in ensuring safety on wet and flooded roads. In the case of low-profile tires in particular, a higher percentage of tread void is necessary to take up the water and to improve the protection against aquaplaning. Cross-grooves for water drainage form “freestanding blocks” in the shoulder area. These shoulder blocks can wear to leave the “sawtooth” pattern as a result of rolling mechanisms under certain operating conditions. These operating conditions include: Long, straight journeys at constant speed Moderate driving style Suspension geometry (alignment/camber).
As the tire rolls along the road, the freestanding blocks deform as they near the tire‘s contact patch. They are compressed as they come into contact with the road. As they lose road contact they “rub” the surface while snapping back into their original shape.
The result is higher wear on the block run-out edge. This wear pattern is more likely to occur on nondriven wheel positions. A minor amount of “saw-tooth” pattern wear is normal and has no discernible effects on comfort. More conspicuous wear of this kind points to specific operating conditions (improper inflation, excessive toe-in, low-wear applications).
Tip: In order to gain even tire wear, the position of the tires on the car should be changed at regular intervals (unless otherwise recommended by the vehicle manufacturer). The position of the tires should be changed in good time, at the latest when changing summer/winter tires.
This wear pattern is found on driven wheels of highly motorised vehicles. Even today’s mid-range cars have modern engines generating high levels of torque and capable of producing high degrees of slip. These high torque levels, during strong acceleration or in stop-start urban traffic, or when accelerating away from traffic lights, can quickly increase wear of the tread centre.
Tip: By rotating the wheels from the powered to the nonpowered axle before it is too late, it is possible to obtain a largely uniform pattern of wear. Always observe the vehicle manufacturer’s recommendations.
The most frequent cause of one-sided wear is an axle geometry out of specification . These deviations develop over time and can be the consequence of , for example, kerb mounting.
Lowering a vehicle in conjunction with lowprofile tyres can also negatively affect wheel alignment. The modified suspension arms (e.g. less rim offset after retrofitting) encourage a tendency for the alignment of the wheels to deviate during driving from the specified data. This might go unnoticed as all wheel alignment values are still found to be within tolerance limits when measured statically on the axle measurement bench. The result may be an increase in nonuniform wear.
The manufacturer’s alignment data applies to vehicles as delivered and may not necessarily apply to customised vehicles.
If a vehicle’s wheels are misaligned, the wheels must be aligned and the deviation corrected.
An impact break involves damage to the carcass (the casing of the tire) inflicted when the tire is in contact with certain obstacles. Usually an externally visible bulge on the sidewall of the tire indicates that cords have been destroyed inside the carcass. If such damage is ignored there is the risk of tire failure at some time in the future, usually delamination of the tread and/or plies or disintegration of the tire sidewall. Damage of this kind is typically caused by driving over objects – like kerbs or speed bumps – at excessive speed and/or at the wrong angle. This overstresses the carcass and can cause individual cords to break. The extent of the damage depends on the speed and angle of impact and on the size of the obstacle. Motorists are usually able to prevent this type of damage themselves. It is inevitable only in very exceptional cases - when an obstacle suddenly appears in front of a vehicle, for example.
Tip: Kerbs and similar obstacles should only be driven over at an obtuse angle and at appropriately slow speed.
Cuts are the result of external influences e.g bad road conditions, protruding bodywork parts or sharp, foreign objects such as stones or glass. You should avoid driving aggresively on unpaved roads. If you discover a cut damage on the tire surface, you should visit your local tire dealer and get your tires checked by an expert immediately.
Punctures are a result of sharp objects on the road e.g. screws, nails or glass which damage the tire. As a consequence the tire could lose pressure. Should you notice that one or more of your tires continuously loses pressure or you discover a screw or nail in the tread, you should visit your local tire dealer as soon as possible to get your tires checked. Continental offers a range of extended mobility systems that help to keep you mobile in the event of a tire failure.
Continental strongly recommend using the appropriate tire for each season. That means driving on summer tires in the warmer time of the year and with winter tires during the cold period. In this way, safety and commercial aspects are maximised under all weather conditions. All Season tires cannot provide the optimal performance under all conditions.
During the warmer weather period (temperatures above 7°C) Continental strongly recommend to use summer tires. Only summer tires can guarantee a high grip levels on wet and dry roads through their special tread patterns and tread compounds. Summer tires also provide high driving stability in curves and optimum mileage performance at summer temperatures.
As winter approaches, drivers should start planning for whatever the weather may throw at them. If you need convincing, just listen to the weather forecasters. They predict that there will be a good mix of snow, ice, rain and dry spells. To cope with this mix of different road conditions, winter tires are strongly recommended.
So, when winter is approaching and the thermometer reaches 7 °C – it’s time to give your summer tires a rest. The roads will normally be cold, wet and slippery and winter tires offer much better grip under these conditions than summer tires. For your own safety, it’s a good idea to change to winter tires from Continental before the start of the season.
Continental strongly recommend using the appropriate tire for each season. That means driving on summer tires in the warmer time of the year and with winter tires during the cold period. In this way, safety and commercial aspects are maximised under all weather conditions.