255/45R20 tire size
A 255/45R20 tire stands 29.04 inches tall overall, on a 20-inch wheel, with a 114.8 mm sidewall and 255 mm of tread across. It turns roughly 695 times per mile.
- Overall diameter
- 29.04″
- 737.5 mm
- Sidewall height
- 114.8 mm
- 45% of 255 mm
- Circumference
- 91.2″
- 2,317 mm
- Revs per mile
- 695
- 432 per km
Reading the number
255 / 45 R 20 │ │ └─ rim diameter, 20 inches │ └──── aspect ratio, sidewall is 45% of width └──────── tread width, 255 mm sidewall = 255 × 0.45 = 114.75 mm diameter = (20 × 25.4) + (2 × 114.75) = 737.5 mm
Sizes that can replace 255/45R20
One rim step away, sorted by how close the rolling diameter stays.
Questions
›What does 255/45R20 mean?
255 is the tread width in millimetres. 45 is the aspect ratio, so the sidewall is 45% of 255 mm, or 114.8 mm. R means radial construction, and 20 is the wheel diameter in inches.
›How tall is a 255/45R20 tire?
29.04 inches, or 737.5 mm overall. That is the 20-inch rim plus a 114.8 mm sidewall at the top and another at the bottom.
›How many revolutions per mile does 255/45R20 do?
About 695 revolutions per mile, from a rolling circumference of 91.2 inches. Speedometers and odometers are calibrated against this figure, which is why changing size shifts both.
›What tires can replace 255/45R20?
Sizes within 3% of its rolling diameter and one rim step away, such as 235/55R19, 275/40R20, 245/45R19. Each is compared in full below.
Comparing against a size not listed? Open the calculator.