Tire Ruler275/45R20 dimensions
| Overall diameter (height) | 29.74″ · 756 mm |
| Section width | 10.83″ · 275 mm |
| Sidewall height | 4.87″ · 124 mm |
| Wheel diameter | 20″ |
| Rim width (rule of thumb) | 7.5–9.5″ |
| Circumference | 93.4″ |
| Revolutions per mile | 678 |
| In inches (flotation style) | 29.7 × 10.8R20 |
How it’s calculated: the sidewall is 45% of the 275 mm width = 123.8 mm (4.87″). Add two sidewalls to the 20″ wheel: 20 + 2 × 4.87 = 29.74″.
Bigger tires than 275/45R20 on 20″ wheels
| Size | Height | Taller by | 60 mph reads |
|---|---|---|---|
| 255/50R20 | 30.0″ | +0.30″ (+1.0%) | 60.6 mph |
| 265/50R20 | 30.4″ | +0.69″ (+2.3%) | 61.4 mph |
| 275/50R20 | 30.8″ | +1.08″ (+3.6%) | 62.2 mph |
| 255/55R20 | 31.0″ | +1.30″ (+4.4%) | 62.6 mph |
| 285/50R20 | 31.2″ | +1.48″ (+5.0%) | 63.0 mph |
“60 mph reads” is your real speed when a speedometer set up for 275/45R20 shows 60. Above about 3% taller, most trucks need a leveling kit or lift, and the speedometer should be recalibrated.
Sizes equivalent to 275/45R20
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 |
|---|---|---|---|
| 245/50R20 | 29.6″ | 9.6″ | −0.3% |
| 255/50R20 | 30.0″ | 10.0″ | +1.0% |
| 265/45R20 | 29.4″ | 10.4″ | −1.2% |
Same height on a different wheel size
Changing wheel size (plus or minus sizing) while keeping the overall height keeps your speedometer right:
- 30x9.50R15: 30.0″ tall on a 15″ wheel (+0.9%)
- 235/75R16: 29.9″ tall on a 16″ wheel (+0.5%)
- 245/70R16: 29.5″ tall on a 16″ wheel (−0.8%)
- 255/70R16: 30.1″ tall on a 16″ wheel (+1.0%)
- 245/65R17: 29.5″ tall on a 17″ wheel (−0.7%)
- 255/65R17: 30.1″ tall on a 17″ wheel (+1.0%)
- 235/70R17: 30.0″ tall on a 17″ wheel (+0.7%)
- 245/60R18: 29.6″ tall on an 18″ wheel (−0.6%)
- 235/65R18: 30.0″ tall on an 18″ wheel (+1.0%)
- 255/55R19: 30.0″ tall on a 19″ wheel (+1.0%)
- 245/55R19: 29.6″ tall on a 19″ wheel (−0.5%)
Popular 275/45R20 comparisons
Frequently asked questions
Is 275/45R20 a 30 inch tire?
Not quite. 275/45R20 is 29.74 inches tall, between a 29 and a 30 inch tire.
What size is 275/45R20 in inches?
275/45R20 is 29.7 inches tall (overall diameter), 10.8 inches wide, with a 4.9 inch sidewall, and fits a 20 inch wheel.
What tire size is equivalent to 275/45R20?
Sizes within 1.5% of the same diameter on a 20" wheel: 245/50R20 (29.6"), 255/50R20 (30.0"), 265/45R20 (29.4"). Check load index and width before swapping.
What rim width fits 275/45R20?
As a rule of thumb, about 7.5–9.5 inches. The tire maker's spec sheet lists the approved range for each model.
How many revolutions per mile does 275/45R20 make?
About 678 revolutions per mile in theory (circumference 93.4 in). Real tires turn slightly more because they flatten under load.