Discover Tyres

What Size Are My Tyres

It’s important to understand how to read the information displayed on your vehicle’s tyres. In doing so, when it comes time to purchasing your next set, you will be able to do so with some understanding as to what size tyres your vehicle requires. Here at BestDrive, we are happy to assist in this process also!

All tyres have a code system, which is moulded into the sidewall of the tyre itself. This provides information regarding the technical capabilities of the tyre and provides information regarding tyre size and construction, load carrying capability and the speed rating.

The most common method used to identify tyres is a series of numbers and letters, which can be found on the sidewall of the tyre.

For example, the tyre may be labelled: 225/50R16 92V

Size descriptions which include either ‘C’ or ‘LT’ in the size description designate the tyres as Commercial Vehicle or Light Truck tyres respectively.

225 is the width of the tyre in millimetres, known as the nominal section width. This measurement is taken from the widest external point of the sidewalls.

50 is the ratio of the tyre’s section height to its section width expressed as a percentage and is also known as the aspect ratio or profile. In this example, the tyre has an aspect ratio of 50, which means that the section height of the tyre is equal to 50% of 225mm, which is approximately 112.5mm.

R is the internal construction - the R stands for Radial. This is the most common type of tyre used in the market today, making up 98% of all tyres sold.

16 is the diameter of the wheel rim in inches. The tyre and wheel diameter must match and must always be confirmed before the tyre is mounted on the wheel.

92 is an index of the maximum load the tyre can carry. The load index is a numerical code associated with the maximum load a tyre can carry at the speed indicated by its Speed Symbol under specified service conditions at speeds up to 210km/h. The load index 92 corresponds to a load of 630kg.

V is the Speed Symbol. Represented by a letter, the symbol indicates the maximum speed at which the tyre can carry a load corresponding to its load index under specified service conditions. The letter V corresponds to a speed of 240km/h.

In some instances, a tyre may also have the letters XL after the speed rating. This stands for Extra Load and means that the tyre can be inflated to a higher pressure, increasing the maximum load carrying capability of the tyre. Typically this relates to vehicles fitted with low aspect ratio tyres.

The size description of one category of Light Truck tyres known as High Flotation tyres is explained below.

Although these are commonly used in the farm and agricultural industries, high flotation tyres have also become increasingly popular in off-road and all-terrain trucks and SUVs.

Using the example of 32x12.50R15LT to read the size of a high flotation tyre:

32 is the overall diameter (in inches)

12.5 is the section width in inches

R indicates that the construction of the tyre is radial, which is the same as passenger and commercial tyres

15 is the rim diameter (in inches)

LT indicates the tyre’s light truck construction

When purchasing new tyres, they will need to be of a similar size to the existing ones. Many speedometers and odometers use the rotation of the wheels to determine how fast, and far, the vehicle is travelling. The figures derived from your dashboard are estimating that the circumference of your tyre matches with those of the manufacturer’s original specifications. Failure to match the existing tyre size may result in accidental speeding. Let the staff at your local BestDrive store assist you in selecting the right size tyres for your vehicle, then have them professionally fitted by one of our qualified technicians.

BestDrive. You drive, we care.

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