What does the 'R' in tires mean?
2 Answers
Tire 'R' stands for radial tire, which is a type of tire structure, different from bias tires, arched tires, and pressure-regulated tires. Car tires are one of the important components of a vehicle, directly in contact with the road surface, working together with the car suspension to mitigate the impact during driving, ensuring good ride comfort and smooth driving. Car tires can be divided into radial tires and bias tires based on their structure. In radial tires, the layers of the carcass cords are arranged parallel to each other in a radial pattern, forming a 90-degree angle with the circumferential line of the tire crown. Bias tires refer to tires where the layers of the carcass cords are arranged in a crisscross pattern, forming a mesh, and creating an angle of 35 to 45 degrees with the circumferential line of the tire crown.
The first time I noticed the letter R on a tire, I also wondered what it stood for. Later, a mechanic told me it's the marking for a radial tire. In regular tires, the fiber cord layers crisscross diagonally, whereas in R-type tires, the cord layers are arranged radially at 90 degrees, like clock hands. This structure relies on a steel belt layer tightly securing the tread, resulting in less tire deformation while driving and a feeling of the car being firmly glued to the road during high-speed turns. After I switched to these tires last year, I clearly felt the steering wheel become lighter, and fuel efficiency improved on the highway compared to before. If the tire sidewall displays numbers like 225/55R17, that R in the middle is the key indicator, signifying that the entire tire construction is based on the radial design principle.
