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TIRE SIZE • EXPLAINED SIMPLY

How to Read Tire Size
Short Tutorial

Tire codes like 205/55R16 91V look confusing at first, but the logic is simple once you see the pattern

This page shows you what each number means and how to avoid mistakes when buying new tires

6 to 8 minRead time

Quick example

Let's decode one common size: P205/60R16. Once you understand this line, you can read almost any tire sidewall

Where to find tire size

The fastest place is the tire sidewall. Look for a format like 205/55R16 or P215/65R15

You can also find the factory sizes on the driver door jamb sticker. This is useful if your current tires are not stock

Close-up of a tire mounted on a wheel showing tire size marking

Width

The first number, like 215, is the tire width in millimeters from sidewall to sidewall

  • Wider tires can offer more grip in dry conditions
  • Wider tires can reduce fuel economy and may hydroplane more easily in heavy rain
  • Changing width can create rubbing issues if clearance is tight

Aspect ratio

The second number, like 65, is the sidewall height as a percentage of the width

For 215/65, the sidewall height is roughly 215 × 0.65, which is about 140 mm

  • Higher ratios usually feel more comfortable
  • Lower ratios usually feel sportier but ride harsher
  • Very low profiles can increase risk of wheel damage on potholes

Construction

The letter, usually R, means radial construction. This is the standard for modern passenger vehicles

If you see something else like B, it is uncommon on most modern cars and you should double check compatibility

Wheel diameter

The last number in the main block, like 15, is the wheel diameter in inches

  • A tire marked 15 fits a 15 inch wheel
  • You cannot mount a 15 tire on a 16 wheel or the opposite

Load index and speed rating

After the size, you often see a pair like 95H. This is the service description

Load indexThe number maps to a maximum weight capacity for the tire. Higher usually means more load capacity
Speed ratingThe letter is the maximum rated speed capability. Match or exceed the factory letter unless a professional confirms otherwise
Safety ruleDo not downgrade load index or speed rating unless a tire professional confirms it is safe for your vehicle

Extra markings

Tires often include extra markings that describe load capability, winter performance, or compliance codes

MarkingMeaningWhy it matters
XLExtra loadHigher load and pressure capability than standard load tires
M+SMud and snowBasic all season marking, not always true winter performance
3PMSFThree peak mountain snowflakeCertified for severe snow traction
DOTCompliance codeIncludes a production date code that helps determine tire age

FAQ

Where do I find my tire size?
Look on the tire sidewall for something like 205/55R16. You can also find factory sizes on the driver door jamb sticker or in the owner manual.
Can I change tire size to something close?
Sometimes, but it can affect speedometer accuracy, handling, and clearance. A safer approach is to keep overall diameter close to stock and confirm fitment with correct load index and speed rating.
What does the R mean in 205/55R16?
R means radial construction, which is the standard for nearly all modern passenger vehicles.
Do I need to match load index and speed rating?
Yes. Match or exceed the factory specs unless a qualified tire professional confirms an acceptable alternative for your vehicle and use case.
What does XL mean on tires?
XL means extra load. The tire is designed to carry higher pressure and load than a standard load tire of the same size.

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