Tire Ruler285/55R20 dimensions
| Overall diameter (height) | 32.34″ · 822 mm |
| Section width | 11.22″ · 285 mm |
| Sidewall height | 6.17″ · 157 mm |
| Wheel diameter | 20″ |
| Rim width (rule of thumb) | 8–10″ |
| Circumference | 101.6″ |
| Revolutions per mile | 624 |
| In inches (flotation style) | 32.3 × 11.2R20 |
How it’s calculated: the sidewall is 55% of the 285 mm width = 156.8 mm (6.17″). Add two sidewalls to the 20″ wheel: 20 + 2 × 6.17 = 32.34″.
Bigger tires than 285/55R20 on 20″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 295/55R20 | 32.8″ | +0.43″ (+1.3%) | 60.8 mph |
| 275/60R20 | 33.0″ | +0.65″ (+2.0%) | 61.2 mph |
| 33x12.50R20 | 33.0″ | +0.66″ (+2.0%) | 61.2 mph |
| 305/55R20 | 33.2″ | +0.87″ (+2.7%) | 61.6 mph |
| 285/60R20 | 33.5″ | +1.12″ (+3.5%) | 62.1 mph |
“60 mph reads” is your real speed when a speedometer set up for 285/55R20 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Sizes equivalent to 285/55R20
Within 1.5% of the same height on a 20″ wheel. Usually interchangeable for the speedometer; check width, load index and clearance.
| Size | Height | Width | Difference |
|---|---|---|---|
| 265/60R20 | 32.5″ | 10.4″ | +0.5% |
| 305/50R20 | 32.0″ | 12.0″ | −1.0% |
| 275/55R20 | 31.9″ | 10.8″ | −1.3% |
| 295/55R20 | 32.8″ | 11.6″ | +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:
- 32x11.50R15: 32.0″ tall on a 15″ wheel (−1.1%)
- 285/70R17: 32.7″ tall on a 17″ wheel (+1.1%)
- 275/70R17: 32.2″ tall on a 17″ wheel (−0.6%)
- 255/75R17: 32.1″ tall on a 17″ wheel (−0.9%)
- 275/65R18: 32.1″ tall on an 18″ wheel (−0.8%)
- 285/65R18: 32.6″ tall on an 18″ wheel (+0.8%)
- 255/70R18: 32.1″ tall on an 18″ wheel (−0.9%)
- 265/70R18: 32.6″ tall on an 18″ wheel (+0.8%)
- 285/45R22: 32.1″ tall on a 22″ wheel (−0.8%)
- 305/45R22: 32.8″ tall on a 22″ wheel (+1.4%)
- 275/50R22: 32.8″ tall on a 22″ wheel (+1.5%)
Popular 285/55R20 comparisons
Frequently asked questions
Is 285/55R20 a 32 inch tire?
Not quite. 285/55R20 is 32.34 inches tall, between a 32 and a 33 inch tire.
What size is 285/55R20 in inches?
285/55R20 is 32.3 inches tall (overall diameter), 11.2 inches wide, with a 6.2 inch sidewall, and fits a 20 inch wheel.
What tire size is equivalent to 285/55R20?
Sizes within 1.5% of the same diameter on a 20" wheel: 265/60R20 (32.5"), 305/50R20 (32.0"), 275/55R20 (31.9"), 295/55R20 (32.8"). Check load index and width before swapping.
What rim width fits 285/55R20?
As a rule of thumb, about 8–10 inches. The tire maker's spec sheet lists the approved range for each model.
How many revolutions per mile does 285/55R20 make?
About 624 revolutions per mile in theory (circumference 101.6 in). Real tires turn slightly more because they flatten under load.