Tire Ruler245/45R18 dimensions
| Overall diameter (height) | 26.68″ · 678 mm |
| Section width | 9.65″ · 245 mm |
| Sidewall height | 4.34″ · 110 mm |
| Wheel diameter | 18″ |
| Rim width (rule of thumb) | 7–8.5″ |
| Circumference | 83.8″ |
| Revolutions per mile | 756 |
| In inches (flotation style) | 26.7 × 9.6R18 |
How it’s calculated: the sidewall is 45% of the 245 mm width = 110.3 mm (4.34″). Add two sidewalls to the 18″ wheel: 18 + 2 × 4.34 = 26.68″.
Bigger tires than 245/45R18 on 18″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 235/50R18 | 27.3″ | +0.57″ (+2.1%) | 61.3 mph |
| 215/55R18 | 27.3″ | +0.63″ (+2.4%) | 61.4 mph |
| 225/55R18 | 27.7″ | +1.06″ (+4.0%) | 62.4 mph |
| 235/55R18 | 28.2″ | +1.50″ (+5.6%) | 63.4 mph |
“60 mph reads” is your real speed when a speedometer set up for 245/45R18 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Sizes equivalent to 245/45R18
Within 1.5% of the same height on an 18″ wheel. Usually interchangeable for the speedometer; check width, load index and clearance.
| Size | Height | Width | Difference |
|---|---|---|---|
| 235/45R18 | 26.3″ | 9.3″ | −1.3% |
Same height on a different wheel size
Changing wheel size (plus or minus sizing) while keeping the overall height keeps your speedometer right:
- 215/70R15: 26.9″ tall on a 15″ wheel (+0.6%)
- 205/70R15: 26.3″ tall on a 15″ wheel (−1.4%)
- 215/65R16: 27.0″ tall on a 16″ wheel (+1.2%)
- 225/60R16: 26.6″ tall on a 16″ wheel (−0.2%)
- 225/55R17: 26.7″ tall on a 17″ wheel (+0.2%)
- 215/55R17: 26.3″ tall on a 17″ wheel (−1.4%)
- 225/45R19: 27.0″ tall on a 19″ wheel (+1.1%)
Frequently asked questions
Is 245/45R18 a 27 inch tire?
Not quite. 245/45R18 is 26.68 inches tall, between a 26 and a 27 inch tire.
What size is 245/45R18 in inches?
245/45R18 is 26.7 inches tall (overall diameter), 9.6 inches wide, with a 4.3 inch sidewall, and fits an 18 inch wheel.
What tire size is equivalent to 245/45R18?
Sizes within 1.5% of the same diameter on an 18" wheel: 235/45R18 (26.3"). Check load index and width before swapping.
What rim width fits 245/45R18?
As a rule of thumb, about 7–8.5 inches. The tire maker's spec sheet lists the approved range for each model.
How many revolutions per mile does 245/45R18 make?
About 756 revolutions per mile in theory (circumference 83.8 in). Real tires turn slightly more because they flatten under load.