245/45R18 tire size
A 245/45R18 tire stands 26.68 inches tall overall, on a 18-inch wheel, with a 110.3 mm sidewall and 245 mm of tread across. It turns roughly 756 times per mile.
- Overall diameter
- 26.68″
- 677.7 mm
- Sidewall height
- 110.3 mm
- 45% of 245 mm
- Circumference
- 83.8″
- 2,129 mm
- Revs per mile
- 756
- 470 per km
Reading the number
245 / 45 R 18 │ │ └─ rim diameter, 18 inches │ └──── aspect ratio, sidewall is 45% of width └──────── tread width, 245 mm sidewall = 245 × 0.45 = 110.25 mm diameter = (18 × 25.4) + (2 × 110.25) = 677.7 mm
Sizes that can replace 245/45R18
One rim step away, sorted by how close the rolling diameter stays.
Questions
›What does 245/45R18 mean?
245 is the tread width in millimetres. 45 is the aspect ratio, so the sidewall is 45% of 245 mm, or 110.3 mm. R means radial construction, and 18 is the wheel diameter in inches.
›How tall is a 245/45R18 tire?
26.68 inches, or 677.7 mm overall. That is the 18-inch rim plus a 110.3 mm sidewall at the top and another at the bottom.
›How many revolutions per mile does 245/45R18 do?
About 756 revolutions per mile, from a rolling circumference of 83.8 inches. Speedometers and odometers are calibrated against this figure, which is why changing size shifts both.
›What tires can replace 245/45R18?
Sizes within 3% of its rolling diameter and one rim step away, such as 255/40R19, 235/45R18, 215/55R17. Each is compared in full below.
Comparing against a size not listed? Open the calculator.