275/60R20 vs 285/55R20

275/60R20 is 0.6" taller than 285/55R20 (2.0%)

Diameter difference−1.97%diameter 32.99" → 32.34"
275/60R20285/55R20
275/60R20285/55R20Difference
Overall diameter32.99"32.34"−0.65"
Section width10.83"11.22"+0.39"
Sidewall height6.50"6.17"−0.32"
Circumference103.6"101.6"−2.0"
Revolutions per mile611624+12
Wheel diameter20"20"±0"

Speedometer

ShowsActualDiff
30 mph29.4 mph−0.6
45 mph44.1 mph−0.9
60 mph58.8 mph−1.2
70 mph68.6 mph−1.4
80 mph78.4 mph−1.6

Gear ratio to match

CurrentEquivalent
3.423.35
3.553.48
3.733.66
4.104.02

285/55R20 is 0.65" shorter than 275/60R20, a −1.97% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.32" (half the diameter change), and the tire needs 0.32" less room above it.

285/55R20 is 0.39" wider. On the same wheel offset about half of that, 0.20", moves toward the suspension and half toward the fender.

Both fit a 20" wheel; the sidewall is 0.32" shorter on 285/55R20.

Details: 275/60R20 in inches · 285/55R20 in inches · change sizes in the calculator

FAQ

What is the difference between 275/60R20 and 285/55R20?

285/55R20 is 0.65" shorter (−1.97%) and 0.39" wider than 275/60R20.

Will 285/55R20 change my speedometer?

Yes, by −1.97%. When the speedometer shows 60 mph you would be going 58.8 mph.

Can I replace 275/60R20 with 285/55R20?

Often yes: the diameter change of −2.0% is within the common 3% guideline. Check the load index, speed rating and clearance.