Tire sizes can be incredibly important when you are shopping for after-market wheels or specialty tires. The wrong-sized tire can cause performance issues and possibly damage to your car. Often, this detail gets overlooked when car owners are out shopping for mud tires, winter tires or fancy new rims. Your maker or dealer may offer a neumático size chart to help take the guesswork out of shopping, but if they don't, then you will need to de-code your tires.
Every tire has a series of letters and numbers stamped into the sidewall, and it's not for decoration. These letters and numbers give a great deal of detail about the vehicle, including where it was made. The numbers that consider tire sizing, though, are found in the first section, usually starting with the letter P (for passenger) or the letters LT (for light truck).
Section width and aspect ratio are the first two numbers that appear in the code. They are typically both measured in millimeters now, although earlier American cars were measured in inches. If your car is older, you may need to look online for a tire size converter to help calculate these measurements in millimeters. The section width is basically a measurement of the tread, from sidewall to sidewall. The aspect ratio is a measurement that reflects the ratio of the sidewall to the section width. So an aspect ratio of 70 means that the sidewall is 70 percent of the section width.