Tire Size Converter: Metric to Inches
To convert a metric tire size to inches, divide the width by 25.4 and add twice the sidewall to the rim: 285/75R16 is about 32.8 × 11.2 inches on a 16-inch rim. To go from inches to metric, 33x12.50R15 means 33 inches tall, 12.5 inches wide, 15-inch rim; the closest metric size is about 315/75R15.
Convert a tire size
The calculator needs JavaScript. The formulas and tables on this page work without it: sidewall = width × aspect ratio ÷ 100, and diameter = rim × 25.4 + 2 × sidewall (in mm).
Overall diameter
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Metric sizes in inches
| Size | Diameter (in) | Diameter (mm) | Width (in) | Sidewall | Revs per mile |
|---|---|---|---|---|---|
| 235/75R15 | 28.9 in | 734 mm | 9.3 in | 176 mm | 698 |
| 265/70R16 | 30.6 in | 777 mm | 10.4 in | 186 mm | 659 |
| 285/75R16 | 32.8 in | 834 mm | 11.2 in | 214 mm | 614 |
| 265/70R17 | 31.6 in | 803 mm | 10.4 in | 186 mm | 638 |
| 285/70R17 | 32.7 in | 831 mm | 11.2 in | 200 mm | 617 |
| 275/60R20 | 33.0 in | 838 mm | 10.8 in | 165 mm | 611 |
| 295/70R18 | 34.3 in | 870 mm | 11.6 in | 206 mm | 589 |
Flotation sizes in metric
| Inch size | Diameter | Width | Closest metric | Metric diameter |
|---|---|---|---|---|
| 31x10.50R15 | 787 mm | 267 mm | 265/75R15 | 30.6 in (-1.1%) |
| 33x12.50R15 | 838 mm | 318 mm | 315/75R15 | 33.6 in (+1.8%) |
| 35x12.50R15 | 889 mm | 318 mm | 315/80R15 | 34.8 in (-0.4%) |
| 33x12.50R17 | 838 mm | 318 mm | 315/65R17 | 33.1 in (+0.4%) |
| 35x12.50R17 | 889 mm | 318 mm | 315/75R17 | 35.6 in (+1.7%) |
| 35x12.50R20 | 889 mm | 318 mm | 315/60R20 | 34.9 in (-0.3%) |
| 37x12.50R17 | 940 mm | 318 mm | 315/80R17 | 36.8 in (-0.4%) |
Closest equivalent = nearest standard width and aspect ratio. Not an exact match; real dimensions differ by make and model.
How the closest metric size is found
Width: the inch width times 25.4, rounded to the nearest metric width step (for example 12.5 in = 317.5 mm, so 315). Aspect ratio: the sidewall ((diameter − rim) ÷ 2) divided by that width, rounded to the nearest 5%. The result is a starting point to compare, not a direct replacement. Always check your vehicle owner’s manual, the tire placard in the door jamb, or a tire shop before changing size.
Frequently asked questions
What is 33x12.50R15 in metric?
A 33x12.50R15 is 838 mm tall and 318 mm wide on a 15-inch rim. The closest standard metric size is about 315/75R15, which works out about 0.6 inches taller. Check the real dimensions of the models you compare.
What is 285/75R16 in inches?
About 32.8 inches tall and 11.2 inches wide, on a 16-inch rim, from the nominal size. In flotation style that is roughly 33x11.2R16, so it is often grouped with 33-inch tires.
Is a 285/70R17 a 33 inch tire?
Nominally it is 32.7 inches tall, so it is often described as a 33-inch tire. Real tires of that size are usually close to that, depending on make and model.
How do I read 33x12.50R15LT?
33 is the overall diameter in inches, 12.50 is the section width in inches, R means radial, 15 is the rim diameter in inches and LT means light truck.
Why do inch and metric sizes not match exactly?
Metric sizes step in 10 mm widths and 5% aspect ratios, while flotation sizes are named in inches. There is rarely an exact metric twin, only the closest one.
Can I swap a flotation size for the closest metric size?
Only after checking that the real diameter, width, load index and speed rating suit your vehicle and wheels. The closest metric size is a starting point for comparison. Ask a tire shop if unsure.
Last updated: October 15, 2026