Tire Ruler235/45R18 dimensions
| Overall diameter (height) | 26.33″ · 669 mm |
| Section width | 9.25″ · 235 mm |
| Sidewall height | 4.16″ · 106 mm |
| Wheel diameter | 18″ |
| Rim width (rule of thumb) | 6.5–8″ |
| Circumference | 82.7″ |
| Revolutions per mile | 766 |
| In inches (flotation style) | 26.3 × 9.3R18 |
How it’s calculated: the sidewall is 45% of the 235 mm width = 105.8 mm (4.16″). Add two sidewalls to the 18″ wheel: 18 + 2 × 4.16 = 26.33″.
Bigger tires than 235/45R18 on 18″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 245/45R18 | 26.7″ | +0.35″ (+1.3%) | 60.8 mph |
| 235/50R18 | 27.3″ | +0.93″ (+3.5%) | 62.1 mph |
| 215/55R18 | 27.3″ | +0.98″ (+3.7%) | 62.2 mph |
| 225/55R18 | 27.7″ | +1.42″ (+5.4%) | 63.2 mph |
“60 mph reads” is your real speed when a speedometer set up for 235/45R18 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Sizes equivalent to 235/45R18
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 |
|---|---|---|---|
| 245/45R18 | 26.7″ | 9.6″ | +1.3% |
| 225/45R18 | 26.0″ | 8.9″ | −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:
- 205/70R15: 26.3″ tall on a 15″ wheel (−0.1%)
- 225/60R16: 26.6″ tall on a 16″ wheel (+1.2%)
- 215/60R16: 26.2″ tall on a 16″ wheel (−0.6%)
- 215/55R17: 26.3″ tall on a 17″ wheel (−0.1%)
Frequently asked questions
Is 235/45R18 a 26 inch tire?
Not quite. 235/45R18 is 26.33 inches tall, between a 26 and a 27 inch tire.
What size is 235/45R18 in inches?
235/45R18 is 26.3 inches tall (overall diameter), 9.3 inches wide, with a 4.2 inch sidewall, and fits an 18 inch wheel.
What tire size is equivalent to 235/45R18?
Sizes within 1.5% of the same diameter on an 18" wheel: 245/45R18 (26.7"), 225/45R18 (26.0"). Check load index and width before swapping.
What rim width fits 235/45R18?
As a rule of thumb, about 6.5–8 inches. The tire maker's spec sheet lists the approved range for each model.
How many revolutions per mile does 235/45R18 make?
About 766 revolutions per mile in theory (circumference 82.7 in). Real tires turn slightly more because they flatten under load.