The tire size is a critical specification that tells you the tire’s type, width, profile, and diameter. Knowing where to find this information helps with shopping for replacements, performing maintenance, and understanding load and speed ratings. The tire size is usually printed on the sidewall of the tire and can be found in several places depending on the tire and vehicle. This guide explains exactly where is the tire size on a tire and how to read it correctly.
Understanding Tire Size Codes
Tire size is presented as a standardized code on the sidewall. A common example is P215/65R15 95H. Each part of the code carries specific information:
- P indicates the tire type, with P meaning passenger car.
- 215 is the tire width in millimeters from sidewall to sidewall.
- 65 is the aspect ratio, representing the height of the sidewall as a percentage of the width.
- R denotes radial construction.
- 15 is the wheel diameter in inches that the tire fits.
- 95 is the load index, indicating how much weight the tire can carry.
- H is the speed rating, showing the maximum safe speed under specified load.
Different vehicle categories use different prefixes, such as LT for light trucks or T for temporary spare tires. Understanding these components helps ensure the correct replacement tire is chosen.
Where To Look On The Tire Sidewall
Most tires display the size near the center of the sidewall. The information is printed in black or white ink, sometimes with raised lettering. The size code can appear in a slightly different location depending on the brand, but it is consistently along the sidewall’s circumference. Look for a string that begins with a letter like P, LT, or T, followed by numbers and letters as described above.
Key tips to locate the tire size quickly:
- Inspect both the outside sidewall and, if accessible, the inside sidewall of the tire.
- Clean the sidewall if grime hides the characters; dirt can obscure the code.
- Check the spare tire (often labeled T or TP for temporary) for its size as well, since it must fit the vehicle’s wheel well.
Common Places On Different Tire Types
While most passenger tyres share a standard format, there are exceptions depending on tire type and vehicle. Here are typical placements and notes for common tire categories:
- Passenger Car Tires: Size appears on the outer sidewall in the P215/65R15 style, often near the center of the tire’s edge.
- Run-Flat and Performance Tires: Size is still on the sidewall, but additional codes may appear nearby indicating reinforced construction or speed ratings.
- Light Truck Tires: Look for a prefix like LT, and the size might be shown as LT265/70R17. The load range and ply information can appear separately on the sidewall.
- Temporary Spare (Donut): The spare often uses a different size from the road tires; the code is printed on the sidewall but may be smaller or abbreviated (e.g., T135/80R-16).
Other Places To Check
In addition to the sidewall, other sources can confirm the tire size, especially if the sidewall is damaged or worn. These sources help ensure the correct size is known:
- Door Jamb Sticker: The vehicle’s door frame decal usually lists the recommended tire size for the factory-installed tires, along with recommended pressure.
- Owner’s Manual: The manual often includes tire size guidelines for the original equipment tires and spare tires.
- Fuel Filler Door or Trunk: Some manufacturers place tire information in the vehicle’s fuel door or trunk area, especially for SUVs and trucks.
- Wheel Well Assets: Some vehicles have the recommended sizes listed on the wheel well or inside the engine bay area, near the fender liners.
Reading The Tire Size And Related Codes
Reading the full tire code provides more than the width and diameter. A typical full code may look like 225/60R18 100H. Here’s how to interpret additional elements you might encounter:
- Load Index (the number, e.g., 100): Higher numbers indicate greater load-carrying capacity.
- Speed Rating (the letter, e.g., H): Indicates the maximum safe operating speed under load.
- UTQG (treadwear, traction, temperature): Rarely found on all tires; when present, it provides wear and performance benchmarks set by the manufacturer.
Understanding these details helps with selecting tires that match vehicle performance requirements and driving conditions.
Tips For Verifying Tire Size During Maintenance
Routine checks can prevent mismatched tires and safety issues. Use these practical steps:
- When purchasing tires, compare the tire size code on the current tires with the new tires to ensure compatibility.
- For a vehicle with mixed tire sizes, consult the owner’s manual or a tire professional; mismatched sizes can affect handling and ABS performance.
- Note the speed rating and load index to avoid overloading or exceeding the vehicle’s design limits.
- Keep a record of the tire size in the vehicle’s maintenance log for quick reference during service appointments.
Frequently Encountered Examples
Below is a quick reference of common tire size examples and what they mean. This helps with faster recognition when you visually inspect tires:
| Example | Meaning |
|---|---|
| P215/60R16 94T | Passenger car, 215 mm width, 60% aspect ratio, radial, 16-inch wheel, load index 94, speed rating T |
| LT265/70R17 121/118S | Light truck, 265 mm width, 70% aspect ratio, radial, 17-inch wheel, dual load index (single/dual), speed S |
| 135/80R-16 C | Temporary spare (often abbreviated), 135 mm width, 80% aspect ratio, radial, 16-inch wheel, C denotes commercial/van use |
These examples illustrate how to decode the tire size and related codes quickly when shopping or performing vehicle maintenance.
Maintaining Accuracy And Safety
Correct tire sizing is essential for vehicle safety, performance, and efficiency. Using the right size ensures proper contact with the road, accurate speedometer readings, and balanced handling. If there is any doubt about the correct size, consult a tire professional or the vehicle manufacturer’s guidance. Always replace tires with the same size, speed rating, and load capacity specified for the vehicle unless a qualified technician approves an alternative.