How to Understand Tire Specification Parameters?
2 Answers
Understanding tire specification parameters can be done as follows: 1. Take 195/65R15-91V as an example: 195 indicates the tire width is 195mm; 65 represents the aspect ratio, which is the percentage of the tire's section height to its width (65%), meaning the tire's profile; "R" stands for RADIAL, indicating it's a radial tire; 15 denotes the rim diameter in inches (15 inches); 91 is the load index; and V signifies the speed rating of the tire. 2. The international standard tire specification generally consists of six parts: "Tire width (mm) + Aspect ratio (%) + Tire type code + Rim diameter (inches) + Load index + Speed rating code."
The sidewall of a tire is marked with codes like 225/55 R17 98V, each of which has a specific meaning. The first three-digit number, 225, refers to the width of the tire in contact with the ground, measured in millimeters. The number after the slash, 55, is the aspect ratio, representing the percentage of the sidewall height relative to the tread width—the larger the number, the thicker the tire. The following R indicates a radial structure, which is standard for most household vehicles today. The 17 denotes the matching rim diameter in inches, a critical measurement that must not be mistaken. The load index, 98, corresponds to a specific weight-bearing capacity, and conversion tables can be found online. The V stands for the speed rating, indicating the maximum speed the tire can withstand. When selecting tires, it's essential to match the original factory parameters, especially the rim size, as even a slight discrepancy can prevent installation. The production date is indicated by the last four digits—for example, 2324 means the tire was manufactured in the 23rd week of 2024. Occasionally, additional markings like the treadwear index or wet traction grade may appear, serving as important references for evaluating tire performance.
