Metric ↔ Flotation Tire Size Converter

Result

Mathematical description: 32.71×11.22R17. The displayed notation is rounded geometry, not a manufacturer-labelled or necessarily purchasable equivalent.

Approximate notation

32.71×11.22R17

Mathematical equivalent only

Rounding the description does not establish commercial availability or physical interchangeability.

Overall tire diameter

830.8 mm

Nominal unloaded diameter

Rim diameter plus two calculated sidewalls.

Sidewall height

199.5 mm

One sidewall

Width multiplied by the profile percentage—not that percentage of rim diameter.

Details

Nominal section width: 285.0 mm
Rim diameter: 431.8 mm
Circumference: 2610.0 mmNominal unloaded circumference, not measured rolling circumference.
Revolutions per mile: 616.6
Revolutions per kilometer: 383.1
Aspect ratio: 70.00%

Results use nominal geometry and the stated conventions. They are dimensional answers, not a fitment, safety or legality check.

What does 33x12.5R17 mean?

It describes a nominal 33-inch overall diameter, 12.5-inch section width and 17-inch rim. It is not a guarantee that an actual tire measures exactly those dimensions.

A metric description gives width in millimetres, profile as a percentage and rim diameter in inches. Flotation-style notation gives nominal overall diameter, nominal width and rim diameter in inches, such as 33x12.5R17.

Metric → flotation calculates the nominal metric geometry first, then expresses its diameter and width in inches. Flotation → metric derives sidewall from half the difference between overall and rim diameter, converts width to millimetres and derives the aspect ratio.

Exact geometry versus a rounded description

An inch is exactly 25.4 mm. The engine retains unrounded numbers; the displayed notation is rounded for readability. Decimal widths or profiles can be mathematical descriptions without matching a standard commercial size.

The converted label is not an assertion that a labelled flotation tire has exactly those dimensions or is interchangeable with the original metric size. Manufacturer labels, measuring rims and actual mounted dimensions differ.

Enter meaningful flotation dimensions

Use diameter × width followed by the rim, for example 33x12.5R17 or 33×12.5-17. Overall diameter must exceed rim diameter so that sidewall is positive. Partial, nonnumeric or out-of-range dimensions pause results.

For a replacement decision, compare actual candidate dimensions in Tire Size Comparison or the full fitment calculator after checking the manufacturer's technical data. Neither notation conversion nor a close nominal diameter approves a tire for a wheel or vehicle.

Example: 285/70R17 expressed in flotation notation

Inputs: Metric tire size: 285/70R17. Metric results below are computed by the same engine as the live tool.

Mathematical description: 32.71×11.22R17. The displayed notation is rounded geometry, not a manufacturer-labelled or necessarily purchasable equivalent.

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Tire Size Converter: calculated example
Measure	Calculated value	Meaning
Approximate notation	32.71×11.22R17	Rounding the description does not establish commercial availability or physical interchangeability.
Overall tire diameter	830.8 mm	Rim diameter plus two calculated sidewalls.
Sidewall height	199.5 mm	Width multiplied by the profile percentage—not that percentage of rim diameter.

Important limitations

Conversions are mathematical approximations, not manufacturer-approved equivalents, purchasable-size claims or vehicle fitment recommendations. Ratings and approved wheel-width ranges are not converted.

See the calculation methodology and testing and accuracy for precision, unit conventions and the distinction between nominal geometry and physical measurement.

Tire Size Converter