How to read tyre size?

The alphanumeric data on the sidewall of the tyre has all the information about your tyre. Know what all those codes mean.

Every time you come across a tyre, the alphanumeric codes engraved on them may get you curious. Have you ever thought what those alphanumeric codes mean? Most of us don’t know as decoding these numbers without any prior knowledge can leave our heads in a spin.

However, contrary to it, deciphering these alphabets and number is pretty much simple. Right from load indexes to constructions type, speed rating and aspect ratios, there’s a whole set of terminologies that combines to show the capabilities and compatibility of a tyre. Let’s bring out the math from an example of a tyre having 205/60 R15 92P etched on its sidewall.

205 = Width

The very first thing you will see on the tyre’s sidewalls inscribed in large bold letters is the main tyre size specs. The 205 signifies the total width of the tyre in mm, across the sidewall.

60 = Aspect ratio

Following the number 205, the 60 indicates the aspect ratio or profile which is written in percentage. The number is the tyre’s cross-section ratio i.e. the comparison of the section height of the tyre corresponding to its width. Here 60 specifies that the height is 55% of the overall tyre’s width.

R = Construction

The R in the above example denotes the Radial Construction of the tyre. You would also see the letter ‘B’ written instead of R. It means the construction type is Bias Ply. However, radial construction types are the most common.

15 = Diameter

The construction type alphabet is followed by the diameter of the wheel measured in inches. Here 15 denotes the rim diameter of the wheel.

92 = Load Index

Afterwards, the number 92 in this tyre marking is the load index. It means the maximum load-carrying capacity of the tyre. Here 92 means a tyre can carry up to 630 kgs of weight when rightly inflated to the recommended level. If you have a different number engraved, you can check the load-carrying capacity by searching the load index chart on the internet.

P – Speed Rating

Lastly, the P denotes the speed rating of the tyre. The letter P means the tyre has a maximum speed limit of 150kmph.

Other crucial information such as brand name and tread wear indicator can also be found on the tyre. The tread wear marking can be found around the circumference in a triangular shape, signifying the tread depth of the tyre. When the tyre tread reaches this point, you need to change the tyre without delay for getting maximum performance and safety.

The tyre measurement explained above will help you find the most appropriate fitment for your vehicle.