Tire Ruler235/55R18 dimensions
| Overall diameter (height) | 28.18″ · 716 mm |
| Section width | 9.25″ · 235 mm |
| Sidewall height | 5.09″ · 129 mm |
| Wheel diameter | 18″ |
| Rim width (rule of thumb) | 6.5–8″ |
| Circumference | 88.5″ |
| Revolutions per mile | 716 |
| In inches (flotation style) | 28.2 × 9.3R18 |
How it’s calculated: the sidewall is 55% of the 235 mm width = 129.3 mm (5.09″). Add two sidewalls to the 18″ wheel: 18 + 2 × 5.09 = 28.18″.
Bigger tires than 235/55R18 on 18″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 225/60R18 | 28.6″ | +0.45″ (+1.6%) | 61.0 mph |
| 255/55R18 | 29.0″ | +0.87″ (+3.1%) | 61.8 mph |
| 235/60R18 | 29.1″ | +0.93″ (+3.3%) | 62.0 mph |
| 245/60R18 | 29.6″ | +1.40″ (+5.0%) | 63.0 mph |
| 235/65R18 | 30.0″ | +1.85″ (+6.6%) | 63.9 mph |
“60 mph reads” is your real speed when a speedometer set up for 235/55R18 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Same height on a different wheel size
Changing wheel size (plus or minus sizing) while keeping the overall height keeps your speedometer right:
- 225/75R15: 28.3″ tall on a 15″ wheel (+0.4%)
- 225/70R16: 28.4″ tall on a 16″ wheel (+0.8%)
- 215/70R16: 27.9″ tall on a 16″ wheel (−1.2%)
- 225/65R17: 28.5″ tall on a 17″ wheel (+1.2%)
- 235/60R17: 28.1″ tall on a 17″ wheel (−0.3%)
Frequently asked questions
Is 235/55R18 a 28 inch tire?
Yes. 235/55R18 is 28.18 inches tall, so it's sold and talked about as a 28-inch tire.
What size is 235/55R18 in inches?
235/55R18 is 28.2 inches tall (overall diameter), 9.3 inches wide, with a 5.1 inch sidewall, and fits an 18 inch wheel.
What tire size is equivalent to 235/55R18?
No common size on an 18" wheel is within 1.5% of 235/55R18's diameter. Use the calculator above to compare any size.
What rim width fits 235/55R18?
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 235/55R18 make?
About 716 revolutions per mile in theory (circumference 88.5 in). Real tires turn slightly more because they flatten under load.