Measurements on Car Tires

Not many people are aware that the tires of the cars they drive are calibrated with tiny writings on the sides. Many people who do know of their existence are not aware of what the measurements mean. Although the meaning is pretty simple, not many bother to go into the technicalities of the tire. Several people tend to be satisfied in the knowledge of whether the car tires provide traction, are inflated and whether they provide a smooth ride. Nevertheless, knowing what the measurements on the tire mean can be very useful in emergencies. The measurements on the tire are a gauge of its model, type and usage pattern. They look like gibberish on the first look, with a weird combination of numbers and alphabets. Below given is an elucidation about the various markings make on the car tire.

Size of the tire

A measurement which reads 250/60/16 on your tire corresponds to its size. 16 refer to the size of the rim, which is 16 inches, over which the tire has to sit. Rims are available in different sizes based on the type of vehicle. Every tire has certain acceptable rim widths that are to be used. Rims are manufactured according to series numbers and each series has a specific range of width. Rim sizes are available in 12, 13, 14, 15, 16 and 17. These standard sizes are suitable for all kinds of vehicles ranging from heavy vehicles to light vehicles. It is very important that the tire be a perfect fit on the rim. If your rim is smaller that the tire, then the tire becomes loose and comes off the rim. The tire also does not give a long life.

Percentage height and width

In the above given example, 60 refers to the percentage of height that the width of the tire attains. In this case, it means that the width of the tire will be 60% its height. Therefore, the height of the vehicle is lowered. You will also find 50% and 70% calibration on the tire. A wider tire is not the best choice for vehicles. Lower the width better will be the life and performance of the vehicle. However, you need to keep the overall height of the vehicle in mind. The vehicle should not be lowered such that it gets hits on minor speed breakers on the road. Moreover, the basic requirement of height varies from one vehicle to other depending upon the weight, load carrying capacity and size. Based on all these factors, the percentage width height should be chosen. Mechanics take up tire size conversion works and they will be able to give you the desired height and width for the tire. However, if you opt to buy a branded tire, then the calibrations are prefixed. Tire conversion is a complicated process that required experience and expertise since the safety of the vehicle depends of the efficiency of the tire. The number 60 on the wheel also indicates that the side wall height is 60mm.

Maximum width of the tire

The first digit 250 refers to the maximum width of the tire at any given point of time. More technically, the number indicates the size of the tire. When inflated fully, the tire reaches a width of 25 cm of 250 millimeters.

Usage calibration

Tires usually sport more measurements than just the basic size of the tire. The measurements on them include the usage pattern as well. A full length measurement on the tire reads something like P250 60 VR 16. As mentioned above 16, 60 and 250 refer to rim size, percentage width and maximum width of the tire when fully inflated, respectively. The numerals on the tire are a measure of the tire’s dimensions. The alphabet “P” refers to the usage pattern. Here, its means “Passenger Load”. Since the load carrying requirement of cargo vehicles are much higher, they are differently calibrated. For all passenger vehicles, the first letter has to be “P”. In some tires, you will find a calibration as “LT”, which stands for light truck. Both the tires are used for passenger automobiles. However, a P rating provides more comfort since the tread patterns are subtle. LT rating is higher on weight carrying capacity.

Speed rating

The next alphabets in the series, VR, stand for speed. Tires are calibrated on two speed scales – below 149 miles per hour and above that value. For tires that are to be used only for speed below 149mph, the calibration is VR. If you require driving at speeds that are above this value, then you need to go in for a “Z” rated tire. In addition to these two ratings, which are found in maximum number of automobiles, there is a special rating for smaller cars as well. For smaller vehicles, which are not permitted to run above a speed of 110mph, you will find a rating saying “H”. You can choose the tire based on your speed requirements.

Other writings on the tire

In addition to these measurements that are engraved on the tire you also find other markings. In most of the tires, the name of the manufacturer is a standard fixture. The commercial name of the company is included along the outermost ring of the tire. The type of construction of the tire is also mentioned on the tire. You will “radial” written on the tire, which means the tire is a radial construction. M&S marking on the tire indicates its suitability for use on mud and snow. In some special tires, you may not find this rating. Tires also contain pressure marking which indicate the maximum pressure that the tire can take while being inflated. The country there the tire is manufactured is also mentioned on the tire. These are the important markings that are present on any tire. Some tires also contain temperature markings; traction rating and tread wear rating. To put it concisely, the markings on the car indicate all aspects of the tire, from size to place of manufacturing.

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