Metric to Inch Tire Size Converter Convert between 225/65R17 and 33x12.5R15 formats

Enter Metric Size
Inch Equivalent
31.6x10.4R17
Metric Size265/70R17
Inch Size31.6x10.4R17
Overall Diameter802.8 mm (31.6")
Section Width265 mm (10.4")
Sidewall Height185.5 mm
Circumference2522.1 mm
Revolutions per Mile638
Rim Diameter17"

How to Use This Converter

This tool converts tire sizes between the two common formats: metric (e.g., 265/70R17) and inch (e.g., 31.6x10.4R17). Select your preferred conversion direction using the tabs above.

Metric to Inch: Select the width, aspect ratio, and rim diameter from the dropdowns. The converter instantly calculates the inch equivalent and shows full specifications for the tire.

Inch to Metric: Select the overall diameter, width, and rim diameter in inches. The converter finds the closest standard metric size and displays complete specifications.

Conversion Formulas

Metric to Inch:
Overall Diameter (in) = ((Width mm × Aspect Ratio ÷ 100 × 2) + (Rim × 25.4)) ÷ 25.4
Width (in) = Width mm ÷ 25.4

Inch to Metric:
Width (mm) = Width in × 25.4 (rounded to nearest standard)
Sidewall (mm) = (Overall Diameter in − Rim in) ÷ 2 × 25.4
Aspect Ratio = Sidewall mm ÷ Width mm × 100 (rounded to nearest standard)

Example

Converting 33x12.5R15 to metric

A popular off-road tire like the 33x12.5R15 has an overall diameter of 33 inches and a width of 12.5 inches on a 15-inch rim. Converting to metric: width = 12.5 × 25.4 = 317.5mm (nearest standard: 315mm), sidewall = (33 - 15) / 2 = 9" = 228.6mm, aspect ratio = 228.6 / 315 × 100 = 72.6 (nearest standard: 70). The metric equivalent is approximately 315/70R15.

Frequently Asked Questions

To convert a metric tire size like 265/70R17 to inches: (1) Calculate the sidewall height: 265 × 0.70 = 185.5mm. (2) Convert to inches: 185.5 ÷ 25.4 = 7.3". (3) Calculate overall diameter: (7.3 × 2) + 17 = 31.6". (4) Convert width: 265 ÷ 25.4 = 10.4". The inch equivalent is approximately 31.6x10.4R17. Use our calculator above for instant, precise conversions.
To convert an inch tire size like 33x12.5R15 to metric: (1) Convert width to mm: 12.5 × 25.4 = 317.5mm, round to nearest standard width: 315mm. (2) Calculate sidewall: (33 - 15) ÷ 2 = 9" = 228.6mm. (3) Calculate aspect ratio: 228.6 ÷ 315 × 100 = 72.6, round to nearest standard: 70. The metric equivalent is approximately 315/70R15.
Metric sizing (like 225/65R17) is the international standard used for most passenger cars and modern SUVs. Inch sizing (like 33x12.5R15) is a traditional American format still popular for off-road, truck, and Jeep tires. Inch sizing makes it easy to quickly understand the overall diameter and width, while metric sizing provides more precise specification of the aspect ratio.
Not always. Metric tire sizes use standardized widths and aspect ratios (225, 235, 245... and 30, 35, 40...), so converting an inch size to metric may not produce an exact match. For example, a 33x12.5R15 converts to approximately 318/72R15, but the nearest standard metric size would be 315/70R15, which has a slightly different overall diameter. Our converter shows the closest standard metric equivalent.

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