How to Choose the Right Tyre Size for Your Car: Sidewall Markings Decoded
Every tyre carries a code on its sidewall that holds critical information about its dimensions, construction type, load capacity, and maximum speed rating. Selecting an improper tyre size can alter your speedometer accuracy, increase fuel consumption, degrade braking performance, or cause suspension rubbing.
Decoding the Sidewall: Example 195/65 R15 91V
- 195: Section width in millimeters from sidewall to sidewall across the tread.
- 65: Aspect ratio (profile). The sidewall height is 65% of the 195mm section width (approx. 126.75mm).
- R: Radial construction — standard for all modern passenger vehicles.
- 15: Wheel rim diameter in inches that the tyre is engineered to fit.
- 91: Load Index — indicates a maximum load rating of 615 kg per tyre.
- V: Speed Symbol — rated for safe sustained speeds up to 240 km/h.
Where to Find Your Vehicle's Factory Size
Before purchasing tyres, always verify the manufacturer-specified tyre size. You can find this in three places:
- On the sticker affixed to the driver's side B-pillar door jamb.
- Inside the vehicle owner's handbook under "Specifications".
- Inside the fuel filler flap door.
Should You Upsize Your Tyres?
Many motorists consider "plus-sizing" to achieve wider contact patch grip and sporty aesthetics. The golden rule of tyre upsizing is to keep the overall rolling diameter within ±2% of the original factory tyre. Exceeding this limit causes speedometer inaccuracies and premature suspension wear.