How do I know which tire size fits my car?

Take 205/55 R16 91V as an example: 205 is the tire width in millimeters, 55 is the aspect ratio (sidewall height as a percentage of width), R16 is the rim diameter in inches, 91 is the load index (615 kg per tire), and V is the speed rating (up to 240 km/h). The safest starting point is your car’s door jamb sticker or owner’s manual, both of which list the manufacturer’s recommended size.

Never deviate from the rim diameter figure without professional consultation — this is one of the most serious wrong tire size consequences, as an incorrect rim fit creates an immediate safety risk and can make the vehicle undrivable. For online purchases, always use the retailer’s fitment checker tool by entering your license plate or VIN before adding anything to your cart. Reputable sellers build this step into the checkout process specifically to prevent costly returns and safety issues.