245/40R18 Tire Size
Dimensions of a 245/40R18 tire in inches and millimeters, with equivalent and plus sizes.
245/40R18 dimensions
A 245/40R18 tire is 245 mm wide with a sidewall that is 40% of the width (98 mm), mounted on a 18-inch rim. Its overall diameter is about 25.72 inches (653 mm), so it is roughly a 25.7-inch tall tire.
| Overall diameter | 25.72 in | 653 mm |
|---|---|---|
| Section width | 9.65 in | 245 mm |
| Sidewall height | 3.86 in | 98.0 mm |
| Rim diameter | 18 in | 457 mm |
| Circumference | 80.8 in | 2052 mm |
| Revolutions | 784 per mile | 487 per km |
Equivalent sizes on a 18-inch rim
These sizes stay within ±3% of the 245/40R18 diameter on the same rim — the range most tire shops use. Not every size is made in every tire model, and only sizes approved for your vehicle (with the right load and speed rating) should be fitted.
| Size | Diameter | mm | Difference |
|---|---|---|---|
| 225/45R18 | 25.97 in | 660 mm | +1.0% |
| 235/40R18 | 25.40 in | 645 mm | -1.2% |
| 255/40R18 | 26.03 in | 661 mm | +1.2% |
| 265/35R18 | 25.30 in | 643 mm | -1.6% |
| 235/45R18 | 26.33 in | 669 mm | +2.4% |
| 225/40R18 | 25.09 in | 637 mm | -2.4% |
| 265/40R18 | 26.35 in | 669 mm | +2.4% |
| 255/35R18 | 25.03 in | 636 mm | -2.7% |
Plus and minus sizes
Changing the rim size? These options on 17-, 19- and 20-inch rims keep the overall diameter within ±3%.
| Size | Diameter | mm | Difference |
|---|---|---|---|
| 245/35R19 | 25.75 in | 654 mm | +0.1% |
| 245/45R17 | 25.68 in | 652 mm | -0.1% |
| 275/40R17 | 25.66 in | 652 mm | -0.2% |
| 245/30R20 | 25.79 in | 655 mm | +0.3% |
| 235/30R20 | 25.55 in | 649 mm | -0.6% |
| 275/30R19 | 25.50 in | 648 mm | -0.9% |
| 235/35R19 | 25.48 in | 647 mm | -0.9% |
| 275/25R20 | 25.41 in | 646 mm | -1.2% |
| 255/30R20 | 26.02 in | 661 mm | +1.2% |
| 255/35R19 | 26.03 in | 661 mm | +1.2% |
Compare 245/40R18 with another size →
Frequently asked questions
How tall is a 245/40R18 tire?
About 25.72 inches (653 mm) in overall diameter.
How wide is a 245/40R18 tire?
The section width is 245 mm, about 9.6 inches.
What size can replace 245/40R18?
On the same rim, 225/45R18 is the closest size (+1.0% diameter). Use only sizes approved for your vehicle.
How many revolutions per mile does a 245/40R18 tire make?
About 784 revolutions per mile (487 per km).
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