275/55R20 tire size
A 275/55R20 tire stands 31.91 inches tall overall, on a 20-inch wheel, with a 151.3 mm sidewall and 275 mm of tread across. It turns roughly 632 times per mile.
- Overall diameter
- 31.91″
- 810.5 mm
- Sidewall height
- 151.3 mm
- 55% of 275 mm
- Circumference
- 100.2″
- 2,546 mm
- Revs per mile
- 632
- 393 per km
Reading the number
275 / 55 R 20 │ │ └─ rim diameter, 20 inches │ └──── aspect ratio, sidewall is 55% of width └──────── tread width, 275 mm sidewall = 275 × 0.55 = 151.25 mm diameter = (20 × 25.4) + (2 × 151.25) = 810.5 mm
Questions
›What does 275/55R20 mean?
275 is the tread width in millimetres. 55 is the aspect ratio, so the sidewall is 55% of 275 mm, or 151.3 mm. R means radial construction, and 20 is the wheel diameter in inches.
›How tall is a 275/55R20 tire?
31.91 inches, or 810.5 mm overall. That is the 20-inch rim plus a 151.3 mm sidewall at the top and another at the bottom.
›How many revolutions per mile does 275/55R20 do?
About 632 revolutions per mile, from a rolling circumference of 100.2 inches. Speedometers and odometers are calibrated against this figure, which is why changing size shifts both.
›What tires can replace 275/55R20?
No common alternative sits within the 3% substitution rule at one rim step from this size.
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