How to Read Car Tire Size?
4 Answers
Tire size is printed on the sidewall. There are three methods to check the size and dimensions, as detailed below: 1. For example, 34*7 represents a high-pressure tire, while 7.50-20 indicates a low-pressure tire. 2. 'D' is used for light vehicles, 'F' for medium-sized vehicles, and 'G' refers to standard vehicles. 3. 'H', 'L', and 'J' are used for large luxury and high-performance vehicles. Below is an introduction to the main knowledge about tires: 1. The international standard tire code, expressed in millimeters, represents the section height and aspect ratio percentage. (1) For small cars with a displacement between 0.8-1.5, the corresponding front tire specifications range from 155/65R1373T to 175/70R1477H. (2) For large cars with a displacement between 1.6-6.0, the tire specifications range from 185/60R14 to 245/50R18. 2. There are many ways to represent tire specifications, with four more common ones: imperial, German, metric, and American systems.
As a seasoned driver with years of experience, reading tire sizes is quite straightforward—it's all about the alphanumeric markings on the tire sidewall, such as P215/65R15 95H. 'P' stands for passenger vehicle tires, sometimes omitted; '215' is the tire width in millimeters, representing the widest point of the tire; '65' is the aspect ratio, meaning the sidewall height is 65% of the width; 'R' denotes radial construction, which most modern cars use; '15' is the rim diameter in inches and must match your car's wheels. Finally, '95H' indicates the load index and speed rating—'95' shows the maximum load capacity in kilograms, while 'H' is the top speed rating. When driving, I regularly check these markings to ensure they're correct, as incorrect sizes can affect handling, make turns unstable, and increase fuel consumption. Tires also have wear indicators showing tread depth—if it's below 1.6mm, replace them immediately. Safety always comes first.
As a DIY car repair enthusiast, I can directly check the tire size by looking at the sidewall markings, with common formats like 195/65R15. If the markings are faded, I measure the width and rim diameter myself using a tape measure. The width is measured in millimeters at the widest point of the tire shoulder, and the rim diameter is measured in inches at the central part of the wheel hub. Incorrect sizing can cause the tire to rub against the suspension, lead to excessive vibration while driving, or even damage electronic components like the ABS system. Once, I tried to save money by installing a smaller tire size and nearly lost control. Tire size also includes the load index, which shouldn't be overlooked—overloading can easily cause a blowout. Before buying new tires, I recommend taking a photo of the original tire to the store for comparison to ensure consistent sizing. For regular car maintenance, check tire pressure and size matching monthly to avoid potential hazards.
Safety first, correct tire size is crucial for driving safety. Look for markings like 205/55R16: the first number indicates width in millimeters, affecting grip; the aspect ratio determines sidewall cushioning; the rim size must match the vehicle. Oversized tires may rub against the suspension, while undersized ones increase braking distance. ABS and stability control rely on standard sizes to function properly. Check tread depth—below 1.6mm is dangerous. Always glance at the sidewall imprint before driving to confirm the correct tires are installed.
