Use our tire size converter to convert metric tire sizes to inches or estimate metric dimensions from an inch-based flotation tire size.
Enter a metric size such as 225/60R17 to calculate its approximate overall diameter, width, sidewall height, and inch-format dimensions. You can also enter a size such as 33×12.50R15 to estimate the corresponding metric width and aspect ratio.
Metric Tire Size to Inches
Enter a metric tire size such as 225/60R17.
Inch Tire Size to Metric
Enter an inch-based flotation size such as 33×12.50R15.
Important: Tire Size Conversion Is Approximate
Metric and flotation tire sizes do not always have exact one-to-one equivalents. Manufacturers may produce slightly different actual dimensions even when the size markings appear similar.
Use the calculated conversion for comparison and research, then verify an available tire size and its published dimensions before purchasing.
How to Use the Tire Size Converter
The tire size converter works in both directions. Use the first section to convert a metric tire size into approximate inch dimensions. Use the second section to estimate metric dimensions from an inch-based flotation size.
Results update automatically as you change the values, so the displayed tire size and calculated dimensions always stay together.
Metric Tire Sizes Explained
A metric tire size contains three primary measurements. In 225/60R17, 225 is the nominal tire width in millimeters, 60 is the aspect ratio, and 17 is the wheel diameter in inches.
The aspect ratio means the sidewall height is approximately 60% of the nominal 225 mm tire width.
Converting Metric Tire Size to Inches
Metric tire width can be converted to inches by dividing the millimeter width by 25.4. Overall diameter requires an additional calculation using the tire's aspect ratio and wheel diameter.
For example, a 225/60R17 tire has a nominal width of approximately 8.86 inches and a calculated overall diameter of approximately 27.63 inches.
What Is an Inch or Flotation Tire Size?
Some truck and off-road tires use a flotation-style size such as 33x12.50R15. In this format, 33 represents approximate overall tire diameter in inches, 12.50 represents nominal tire width in inches, and 15 represents wheel diameter.
Converting Inch Tire Sizes to Metric
Converting a flotation size to metric requires estimating the tire width in millimeters and calculating the sidewall height from the difference between overall tire diameter and wheel diameter.
The calculated aspect ratio can then be used to describe an approximate metric-style size. The result should be treated as a dimensional comparison rather than a guaranteed commercially available tire size.
Why Tire Conversions Are Not Always Exact
Tire size markings describe nominal dimensions rather than guaranteed physical measurements. Actual diameter and width can vary between tire manufacturers, models, tread patterns, load ranges, and wheel widths.
An exact mathematical conversion may also produce a metric width or aspect ratio that is not manufactured as a standard tire size. Always compare manufacturer-published dimensions when choosing an actual replacement tire.
Tire Size Converter vs. Tire Size Comparison
A tire size converter changes the way one tire size is expressed. If you need to compare two actual tire sizes, use our Tire Size Comparison Calculator.
You can also use our Tire Diameter Calculator when you only need the dimensions of one metric tire size.
Tire Size Converter FAQ
What is 225/60R17 in inches?
A 225/60R17 tire is approximately 8.86 inches wide and has a calculated overall diameter of about 27.63 inches.
Can I convert 33x12.50R15 directly to one metric tire size?
You can calculate approximate metric dimensions, but there may not be one exact standard metric equivalent. Actual available sizes and manufacturer dimensions should be checked before purchasing.
Is tire width in metric sizes measured in millimeters?
Yes. The first number in a size such as 225/60R17 represents a nominal section width of 225 millimeters.
Are calculated tire dimensions exact?
No. They are mathematical estimates. Actual mounted dimensions vary with tire design, manufacturer tolerances, wheel width, inflation pressure, load, and tread construction.
Explore More Tire Tools
Learn more about tire sizes, calculate dimensions with our Tire Diameter Calculator, compare two sizes with our Tire Size Comparison Calculator, or browse all tire and wheel calculators.
Verify the Actual Tire Before Installation
A converted tire size does not confirm vehicle fitment or guarantee that an equivalent commercial tire exists. Verify manufacturer dimensions, load rating, speed rating, wheel compatibility, clearance, and specifications for your exact vehicle before purchasing or installing a different tire size.