What Does the Car Tire Model Number Represent?
3 Answers
"Taking the tire model 195/55R15 as an example, 195 represents the tire width of 195 millimeters, 55 indicates the aspect ratio of 55%, R stands for radial tire type, and 15 is the rim diameter, meaning this tire model fits a 15-inch rim. If there is an additional number followed by +V, the number represents the maximum load a tire can bear. The higher the number, the greater the load capacity. V denotes the speed rating, which is the maximum speed the tire can safely handle. Different numbers correspond to different speed levels, and exceeding the tire's maximum speed may lead to dangers such as blowouts. Typically, there are also four digits preceding the data, such as 2515, which indicate the tire's manufacturing date. 2515 means the tire was produced in the 25th week of 2015. There may be other letters or numbers, but these usually represent brand names or brand identifiers. Tires cannot be swapped arbitrarily. Car tire specifications are determined based on comprehensive analysis and testing of vehicle suspension data, transmission, and engine gear ratios, among other factors. Swapping tires of different models can affect the car's stability, load capacity, power performance, steering angle, braking distance, and suspension height. For driving safety, it is crucial not to change tires randomly. "
As a veteran driver with twenty years of experience, I can explain tire specifications with my eyes closed. Take 205/55R16 91V for example: 205 is the tread width in millimeters—the wider the better the grip, but it consumes more fuel; 55 is the aspect ratio—the smaller this number, the thinner the tire, so be careful over speed bumps; R stands for radial construction, which is pretty much standard these days; 16 is the wheel diameter in inches; 91 is the load index, which you’d need to check a table for, indicating a maximum load of 615 kg per tire; V is the speed rating, meaning it can handle up to 240 km/h. When replacing tires, the specifications must match the factory standards, or you won’t pass the annual inspection—last time I saw someone use the wrong specs and their speedometer became inaccurate. My advice is to replace tires once the wear indicators on the sidewall become visible—don’t skimp on this expense.
When I researched tire parameters while modifying the wheels the year before last, I discovered that the model numbers contain a wealth of information. Taking 235/45ZR18 as an example, the 235mm width affects cornering stability, the 45% aspect ratio balances comfort and handling, ZR denotes a high-performance tire (regular tires are marked with R), and 18 inches is suitable for large rims. Pay special attention to the last letter; a W-rated tire can withstand higher speeds than a V-rated one. When modifying, ensure the overall wheel diameter change is kept within 3%. A friend of mine switched to low-profile tires and ended up with a bulge after hitting a pothole, so he had to install a tire pressure monitoring system for peace of mind. The tire sidewall also shows the production date, such as 3223 indicating the 32nd week of 2023.
