All tyres look the same at first glance – round and black – but look a little closer, and you’ll be amazed at the variety. So how do you decide what tyres to buy when it’s time to change them?

In general, it’s best to replace your current tyres with a similar type. Information about the tyres on your car can be found in the form of markings stamped onto the tyre sidewall. And thankfully, all manufacturers follow the same marking formula, which lets you derive the following information:

Vehicle type
Light-truck tyres are marked with “LT” and passenger car tyres with “P”.

Tyre width
Measured in millimetres. Co with the size of tyre recommended by the car manufacturer. A wider tyre will give your car better grip on dry roads, but your mileage will suffer. Tyres that are too wide may rub against the car body. Narrow tyres have better traction in bad weather, but too-narrow ones pose a safety risk.

Aspect ratio
A tyre’s aspect ratio determines how tall the sidewall is, and it is calculated by dividing the height of the sidewall by the tyre’s width. A lower, stiffer sidewall will improve cornering, but will make the ride a little harsher. Changing the aspect ratio too much can render the speedometer inaccurate.

Speed rating
The speed rating represents the maximum speed the tyre can sustain at full load. It also indicates the tyre's ability to dissipate heat. One with a higher speed rating can dissipate more heat on long highway journeys.

Q – Up to 160 kmh
R – Up to 170 kmh
S – Up to 180 kmh
T – Up to 190 kmh
U – Up to 200 kmh
H – Up to 210 kmh
V – Up to 240 kmh
Y – Up to 270 kmh 

Load index
The load index figure denotes the maximum load capacity of a tyre when driven at maximum speed. You shouldn’t replace a tyre with one that has a lower load-carrying capacity.

Construction
This refers to how the tyre was put together. “R” stands for radial tyres, meaning that the body ply cords run radially across from bead to bead. “B” indicates bias construction, where the body ply cords run diagonally across from bead to bead and the ply layers alternate in direction.