What is the size of my tyre?
Your tyre size is printed on the sidewall as a size code such as 205/55R16. To know the exact size for replacement, read the markings on the tyre; you can also find it on the vehicle’s door placard or in the owner’s manual.
Tyre sizing combines width, profile, and wheel diameter, and may also include load and speed ratings. This article explains how to read the size code, where to find it on your vehicle, and how to choose a safe, compatible replacement.
How to Read Your Tyre Size
These elements tell you what the numbers mean and help you compare tyres. The most common format is width/seriesRdiameter, optionally followed by load index and speed rating.
- Tyre width in millimetres (e.g., 205)
- Aspect ratio, the height as a percentage of the width (e.g., 55)
- Construction type (R = radial)
- Rim diameter in inches (e.g., 16)
- Load index and speed rating (e.g., 91V)
- Optional markings like XL (extra load) or RFT (Run-Flat)
Understanding these parts helps you interpret a tyre size code and compare options when shopping.
Where to Find Your Tyre Size
There are several reliable places to look for the official tyre size, which ensures you match factory recommendations and maintain performance and safety.
- On the sidewall of each tyre (the most immediate reference).
- On the driver’s door jamb placard, which lists the recommended sizes for your vehicle.
- In the owner’s manual or on the tyre placard inside the glove box or fuel door.
- On the spare tyre, which may have a different size; if you plan to use it for longer trips, you should know its size too.
When replacing tyres, start with the size shown by the vehicle manufacturer and the sidewall markings to ensure fit and safety.
Replacing or Upgrading: What You Need to Know
If you’re considering a different size, you must meet certain criteria to avoid problems with handling, speedometer accuracy, and ABS/ESC systems.
- Try to match the original width, aspect, and rim diameter as a starting point.
- The overall diameter should be within about 3% of the original to maintain accurate speed readings and braking performance.
- Check the load index and speed rating; they must meet or exceed the original specifications.
- Consider guidance from the vehicle manufacturer or a tyre professional, especially for performance or off-road tyres.
- Be aware that upgrading to a wider tyre on the same wheel can cause rubbing and may require suspension or fender clearance checks.
Always confirm fit with a qualified tyre professional before purchasing new tyres or wheels.
Common Tyre Sizes by Vehicle Type
While exact sizes vary by model, these ranges illustrate typical sizes you’ll encounter on different vehicle classes. Always verify against your car’s specification.
- Small cars and city cars: about 165/65R14 to 185/60R15
- Compact cars and sedans: about 195/65R15 to 205/60R16
- Sedans and family cars: about 205/55R16 to 225/50R17
- SUVs and crossovers: about 235/55R18 to 265/65R17 and larger
Sizes vary by model year and trim, so use official placards and manuals for accuracy.
Summary
In short, your tyre size is printed on the tyre sidewall and on your vehicle’s placard. Read the code to understand width, height, construction, and diameter, and ensure replacement tyres meet load and speed requirements. If in doubt, consult a tyre professional for guidance to maintain safety and performance.
For readers seeking quick action: locate the sidewall code on your current tyres (for example, 205/55R16 91V) and cross-check this with the door placard on the driver's side door frame or your vehicle manual. That will guide you to the correct replacement size and any acceptable alternatives.
