245/60R20 vs 275/55R20

275/55R20 is 0.3" taller than 245/60R20 (1.1%)

Diameter difference+1.06%diameter 31.57" → 31.91"
245/60R20275/55R20
245/60R20275/55R20Difference
Overall diameter31.57"31.91"+0.33"
Section width9.65"10.83"+1.18"
Sidewall height5.79"5.95"+0.17"
Circumference99.2"100.2"+1.1"
Revolutions per mile639632−7
Wheel diameter20"20"±0"

Speedometer

ShowsActualDiff
30 mph30.3 mph+0.3
45 mph45.5 mph+0.5
60 mph60.6 mph+0.6
70 mph70.7 mph+0.7
80 mph80.8 mph+0.8

Gear ratio to match

CurrentEquivalent
3.423.46
3.553.59
3.733.77
4.104.14

275/55R20 is 0.33" taller than 245/60R20, a +1.06% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.17" (half the diameter change), and the tire needs 0.17" more room above it.

275/55R20 is 1.18" wider. On the same wheel offset about half of that, 0.59", moves toward the suspension and half toward the fender.

Both fit a 20" wheel; the sidewall is 0.17" taller on 275/55R20.

Details: 245/60R20 in inches · 275/55R20 in inches · change sizes in the calculator

FAQ

What is the difference between 245/60R20 and 275/55R20?

275/55R20 is 0.33" taller (+1.06%) and 1.18" wider than 245/60R20.

Will 275/55R20 change my speedometer?

Yes, by +1.06%. When the speedometer shows 60 mph you would be going 60.6 mph.

Can I replace 245/60R20 with 275/55R20?

Often yes: the diameter change of +1.1% is within the common 3% guideline. Check the load index, speed rating and clearance.