How to understand tire ratings?

[OJace]

V and H refer to the speed rating of the tire, which indicates the maximum speed at which the tire can carry a specified load under specified conditions. 91 and 85 refer to the load index of the tire, which is the maximum weight the tire can bear. The load rating is molded on the sidewall.

[SanLily]

There's a string of mysterious codes on the tire sidewall, such as 225/45 R17 91V. The last letter V is the speed rating symbol, indicating a maximum speed of 240 km/h without tire failure. Don't overlook the initial three-digit number—91 represents the load index, meaning each tire can bear 615 kg. I suggest checking the sidewall letters while inspecting tread depth; R marks a radial tire, and the number before the slash indicates the tread width. Winter tires feature a mountain snowflake symbol, while all-season tires are marked with M+S (mud and snow) notation. Recently, when changing tires, I noticed the four-digit number after DOT is more crucial—for example, 1523 means the tire was produced in the 15th week of 2023. Tires older than 6 years are considered stock tires.

[OscarMarie]

Last time I changed my car tires, I specifically researched these markings. The most practical is the speed rating alphabet, where H stands for 210km/h and V for 240km/h. Remember that the load index 90 corresponds to 600kg load capacity, and 91 to 615kg. Nowadays, tire sidewalls also display a treadwear index - a TREADWEAR 280 tire is more wear-resistant than a 400. It's advisable to check for puncture-resistant layer markings; run-flat tires marked with RFT or RF are more expensive but offer peace of mind. Original equipment manufacturer (OEM) tires with star symbols engraved on the sidewall are the most reliable but costly, while economy tires with triangle symbols have shorter lifespans. Note that higher TREADWEAR values indicate better wear resistance, and TRACTION A-grade offers the best wet grip performance.

[OLyla]

To identify truck tires, look for the LT prefix marking, such as LT245/75R16. The last two digits indicate the rim size, and the letter E represents 8-ply strength. Light truck tires with a load index like 110/109Q have dual parameters: the first number is the single-wheel load capacity, and the second is the dual-wheel load capacity. Maintain a tread depth of at least 1.6mm—it's recommended to carry a caliper for measurement. Aligning the red dot on the tire sidewall with the wheel's valve stem is the easiest method. Off-road tires marked with M+S offer better anti-slip performance in rainy conditions, but highway tires are more fuel-efficient. Pay attention to aging cracks, especially around the tire shoulders.