Numbers on car tyres -- What do they mean? | The Financial Express

# Numbers on car tyres — What do they mean?

## Have you ever looked at a tyre and wondered what the various numbers mean? Here are the tyre size, profile, rim, and speed ratings explained.

When you look at your car tyres, they have the branding and the model name. Most stop at that point. However, to the more curious minds, they catch onto other details such as numbers and alpha-numeric signs, making them ponder what they mean.

Many know that the numbers indicate the size of the tyre, however, for those who don’t, here’s a quick guide to make you an expert.

## Numbers on car tyres and their meaning explained

The first three numbers denote the width of the tyre. Various cars use different widths of tyres depending on the model. High-end cars with larger engine displacement use wider tyres so that there’s more contact patch with the road to put down the power better.

While wider tyres may look cool, one needs to keep in mind that the larger the tyre is, the more unsprung mass the vehicle has, directly affecting performance and handling. Wide tyres on small displacement cars will only take away the performance, so stick to what the manufacturer recommends.

The second two digits denote the height of the tyre in terms of percentage. Take for example a tyre that measures 255/75, the tyre is 75 percent of 255 tall. Usually, performance cars have a lower profile or height, while SUVs have a higher profile.

The alphabet that follows denotes the construction of the tyre, which in this case is radial, hence ‘R’. All modern cars run on radial tyres, so the ‘R’ is common. There are other constructions as well, such as B for Bias belt and D for Diagonal, but these are for older cars. Following the ‘R’ comes the size of the rim, or the diameter of the tyre, measured from the inside. In our example, it’s 15, so the wheel fits a 15-inch rim.

The following two digits represent the load capacity of the tyre. This indicates the maximum load the tyres are meant to carry, and in this case, 89 is rated to carry 580kg. This is followed by an alphabet, denoting the speed the tyre is rated for. In our case, the rating is ‘T’, which is meant for a maximum speed of 190kmph.