Tire Ruler235/50R18 dimensions
| Overall diameter (height) | 27.25″ · 692 mm |
| Section width | 9.25″ · 235 mm |
| Sidewall height | 4.63″ · 118 mm |
| Wheel diameter | 18″ |
| Rim width (rule of thumb) | 6.5–8″ |
| Circumference | 85.6″ |
| Revolutions per mile | 740 |
| In inches (flotation style) | 27.3 × 9.3R18 |
How it’s calculated: the sidewall is 50% of the 235 mm width = 117.5 mm (4.63″). Add two sidewalls to the 18″ wheel: 18 + 2 × 4.63 = 27.25″.
Bigger tires than 235/50R18 on 18″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 225/55R18 | 27.7″ | +0.49″ (+1.8%) | 61.1 mph |
| 235/55R18 | 28.2″ | +0.93″ (+3.4%) | 62.0 mph |
| 225/60R18 | 28.6″ | +1.38″ (+5.1%) | 63.0 mph |
| 255/55R18 | 29.0″ | +1.79″ (+6.6%) | 63.9 mph |
| 235/60R18 | 29.1″ | +1.85″ (+6.8%) | 64.1 mph |
“60 mph reads” is your real speed when a speedometer set up for 235/50R18 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Sizes equivalent to 235/50R18
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 |
|---|---|---|---|
| 215/55R18 | 27.3″ | 8.5″ | +0.2% |
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 (−1.5%)
- 225/70R15: 27.4″ tall on a 15″ wheel (+0.5%)
- 215/65R16: 27.0″ tall on a 16″ wheel (−0.9%)
- 225/60R17: 27.6″ tall on a 17″ wheel (+1.4%)
- 215/60R17: 27.2″ tall on a 17″ wheel (−0.3%)
- 235/55R17: 27.2″ tall on a 17″ wheel (−0.3%)
- 225/45R19: 27.0″ tall on a 19″ wheel (−1.0%)
- 235/45R19: 27.3″ tall on a 19″ wheel (+0.3%)
Frequently asked questions
Is 235/50R18 a 27 inch tire?
Not quite. 235/50R18 is 27.25 inches tall, between a 27 and a 28 inch tire.
What size is 235/50R18 in inches?
235/50R18 is 27.3 inches tall (overall diameter), 9.3 inches wide, with a 4.6 inch sidewall, and fits an 18 inch wheel.
What tire size is equivalent to 235/50R18?
Sizes within 1.5% of the same diameter on an 18" wheel: 215/55R18 (27.3"). Check load index and width before swapping.
What rim width fits 235/50R18?
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 235/50R18 make?
About 740 revolutions per mile in theory (circumference 85.6 in). Real tires turn slightly more because they flatten under load.