Tire Ruler285/50R20 dimensions
| Overall diameter (height) | 31.22″ · 793 mm |
| Section width | 11.22″ · 285 mm |
| Sidewall height | 5.61″ · 143 mm |
| Wheel diameter | 20″ |
| Rim width (rule of thumb) | 8–10″ |
| Circumference | 98.1″ |
| Revolutions per mile | 646 |
| In inches (flotation style) | 31.2 × 11.2R20 |
How it’s calculated: the sidewall is 50% of the 285 mm width = 142.5 mm (5.61″). Add two sidewalls to the 20″ wheel: 20 + 2 × 5.61 = 31.22″.
Bigger tires than 285/50R20 on 20″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 245/60R20 | 31.6″ | +0.35″ (+1.1%) | 60.7 mph |
| 275/55R20 | 31.9″ | +0.69″ (+2.2%) | 61.3 mph |
| 305/50R20 | 32.0″ | +0.79″ (+2.5%) | 61.5 mph |
| 285/55R20 | 32.3″ | +1.12″ (+3.6%) | 62.2 mph |
| 265/60R20 | 32.5″ | +1.30″ (+4.2%) | 62.5 mph |
“60 mph reads” is your real speed when a speedometer set up for 285/50R20 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Sizes equivalent to 285/50R20
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 |
|---|---|---|---|
| 255/55R20 | 31.0″ | 10.0″ | −0.6% |
| 245/60R20 | 31.6″ | 9.6″ | +1.1% |
| 275/50R20 | 30.8″ | 10.8″ | −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:
- 31x10.50R15: 31.0″ tall on a 15″ wheel (−0.7%)
- 265/75R16: 31.6″ tall on a 16″ wheel (+1.4%)
- 265/70R17: 31.6″ tall on a 17″ wheel (+1.2%)
- 255/70R17: 31.1″ tall on a 17″ wheel (−0.5%)
- 245/75R17: 31.5″ tall on a 17″ wheel (+0.8%)
- 275/65R17: 31.1″ tall on a 17″ wheel (−0.5%)
- 265/65R18: 31.6″ tall on an 18″ wheel (+1.1%)
- 255/65R18: 31.1″ tall on an 18″ wheel (−0.5%)
- 275/60R18: 31.0″ tall on an 18″ wheel (−0.7%)
- 255/60R19: 31.0″ tall on a 19″ wheel (−0.6%)
- 285/40R22: 31.0″ tall on a 22″ wheel (−0.8%)
Popular 285/50R20 comparisons
Frequently asked questions
Is 285/50R20 a 31 inch tire?
Yes. 285/50R20 is 31.22 inches tall, so it's sold and talked about as a 31-inch tire.
What size is 285/50R20 in inches?
285/50R20 is 31.2 inches tall (overall diameter), 11.2 inches wide, with a 5.6 inch sidewall, and fits a 20 inch wheel.
What tire size is equivalent to 285/50R20?
Sizes within 1.5% of the same diameter on a 20" wheel: 255/55R20 (31.0"), 245/60R20 (31.6"), 275/50R20 (30.8"). Check load index and width before swapping.
What rim width fits 285/50R20?
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 285/50R20 make?
About 646 revolutions per mile in theory (circumference 98.1 in). Real tires turn slightly more because they flatten under load.