275/55R20 tire size: 31.91 in tall
Diameter, sidewall, width and revs per mile for 275/55R20, the common sizes within 3% of its diameter, and what each one does to the speedometer.
275/55R20, in short: 31.91 in (810 mm) tall and 275 mm (10.83 in) wide, with a 5.95 in (151.2 mm) sidewall, for a 20-inch wheel. Circumference is 100.25 in, so it turns about 632 times per mile (calculated from the nominal size).
Calculated from the size: sidewall = 275 × 55% = 151.25 mm; diameter = 2 × 5.955 in + 20 in; revs per mile = 63,360 ÷ (π × diameter).
Sizes within 3% of 275/55R20
11 common sizes come within ±3% of 31.91 in: 3 on the same 20-inch wheel, 3 plus-size and 5 minus-size. The last column is what the speedometer shows when the vehicle, set up for 275/55R20, is doing a true 60 mph.
| Size | Fit | Diameter | Difference | Width | Sidewall | Revs/mile (calc.) | Speedometer at a true 60 |
|---|---|---|---|---|---|---|---|
| 275/55R20 | This size | 31.91 in | - | 275 mm | 5.95 in | 632 | 60.0 mph |
| 255/65R18 | Minus 2 | 31.05 in | -2.69% | 255 mm | 6.53 in | 650 | 61.7 mph |
| 265/65R18 | Minus 2 | 31.56 in | -1.09% | 265 mm | 6.78 in | 639 | 60.7 mph |
| 275/65R18 | Minus 2 | 32.07 in | +0.52% | 275 mm | 7.04 in | 629 | 59.7 mph |
| 285/65R18 | Minus 2 | 32.59 in | +2.12% | 285 mm | 7.29 in | 619 | 58.8 mph |
| 265/70R18 | Minus 2 | 32.61 in | +2.18% | 265 mm | 7.30 in | 619 | 58.7 mph |
| 255/55R20 | Same wheel | 31.04 in | -2.71% | 255 mm | 5.52 in | 650 | 61.7 mph |
| 285/50R20 | Same wheel | 31.22 in | -2.16% | 285 mm | 5.61 in | 646 | 61.3 mph |
| 265/60R20 | Same wheel | 32.52 in | +1.91% | 265 mm | 6.26 in | 620 | 58.9 mph |
| 285/40R22 | Plus 2 | 30.98 in | -2.92% | 285 mm | 4.49 in | 651 | 61.8 mph |
| 285/45R22 | Plus 2 | 32.10 in | +0.59% | 285 mm | 5.05 in | 628 | 59.6 mph |
| 275/50R22 | Plus 2 | 32.83 in | +2.87% | 275 mm | 5.41 in | 614 | 58.3 mph |
A taller tire makes the speedometer read low, a shorter one high. Plus-sizing keeps the diameter close by trading sidewall for wheel. Any replacement needs a load index at least as high as the vehicle's tire placard calls for, and a wheel width the tire is approved for.
275/55R20 compared
275/55R20 side by side with 275/60R20 and 285/55R20: dimension by dimension, and what the swap does to the speedometer.
275/55R20 vs 275/60R20
+3.39% diameter| 275/55R20 | 275/60R20 | Difference | |
|---|---|---|---|
| Overall diameter | 31.91 in | 32.99 in | +1.08 in (+3.4%) |
| Section width | 275 mm | 275 mm | +0 mm |
| Sidewall height | 5.95 in | 6.50 in | +0.54 in |
| Wheel diameter | 20 in | 20 in | +0 in |
| Circumference | 100.2 in | 103.6 in | +3.4 in |
| Revs per mile (calc.) | 632 | 611 | -21 |
275/60R20 is 3.4% taller than 275/55R20. At a true 60 mph the speedometer shows 58.0 mph (it reads low), and when it shows 60 you're doing 62.0 mph.
275/55R20 vs 285/55R20
+1.36% diameter| 275/55R20 | 285/55R20 | Difference | |
|---|---|---|---|
| Overall diameter | 31.91 in | 32.34 in | +0.43 in (+1.4%) |
| Section width | 275 mm | 285 mm | +10 mm |
| Sidewall height | 5.95 in | 6.17 in | +0.22 in |
| Wheel diameter | 20 in | 20 in | +0 in |
| Circumference | 100.2 in | 101.6 in | +1.4 in |
| Revs per mile (calc.) | 632 | 624 | -8 |
285/55R20 is 1.4% taller than 275/55R20. At a true 60 mph the speedometer shows 59.2 mph (it reads low), and when it shows 60 you're doing 60.8 mph.
Which vehicles come with 275/55R20
Vehicles sold in the US that have 275/55R20 as the standard size on these trims, with the page that lists it. The tire placard on the driver's door edge or post has the size, and the load and inflation, for the exact vehicle.
- Ram 1500 2025 model year · Laramie, Limited, Limited Longhorn, Tradesman HFEMavis Tire OE fitment page, 2025 Ram 1500 Laramie (size flagged standard 'S')
- Jeep Wrangler 4xe 2025 model year · Unlimited High Altitude 4xe, Unlimited Backcountry 4xeMavis Tire OE fitment page, 2025 Jeep Wrangler Unlimited High Altitude 4xe (size flagged standard 'S')
- Chevrolet Tahoe 2025 model year · RST Performance Edition (also PPV police)Mavis Tire OE fitment page, 2025 Chevrolet Tahoe RST Performance Edition (size flagged standard 'S')
Vehicles mostly picked from Carscoops: 2025 U.S. car sales, full-year top 25 (Car and Driver data, January 2026).
Questions about 275/55R20 tires
How tall is a 275/55R20 tire?
What is 275/55R20 in inches?
How many revolutions per mile does a 275/55R20 tire make?
What size can replace 275/55R20?
275/55R20 vs 275/60R20: what's the difference?
Which vehicles come with 275/55R20 tires?
How these numbers are worked out
- NHTSA: Tire safety, everything rides on it (reading the sidewall and the placard)
- Tire Rack: How do I calculate tire dimensions?
- Jalopnik: What the 3% rule means for your tires (April 2026)
Checked October 2026. Dimensions are nominal, calculated from the size designation. A real tire's diameter, width and revs per mile vary by brand, tread depth, rim width and load, so check the maker's spec sheet.
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