285/50R20 vs 275/55R20

275/55R20 is 0.7" taller than 285/50R20 (2.2%)

Diameter difference+2.21%diameter 31.22" → 31.91"
285/50R20275/55R20
285/50R20275/55R20Difference
Overall diameter31.22"31.91"+0.69"
Section width11.22"10.83"−0.39"
Sidewall height5.61"5.95"+0.34"
Circumference98.1"100.2"+2.2"
Revolutions per mile646632−14
Wheel diameter20"20"±0"

Speedometer

ShowsActualDiff
30 mph30.7 mph+0.7
45 mph46.0 mph+1.0
60 mph61.3 mph+1.3
70 mph71.5 mph+1.5
80 mph81.8 mph+1.8

Gear ratio to match

CurrentEquivalent
3.423.50
3.553.63
3.733.81
4.104.19

275/55R20 is 0.69" taller than 285/50R20, a +2.21% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.34" (half the diameter change), and the tire needs 0.34" more room above it.

285/50R20 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 0.34" taller on 275/55R20.

Details: 285/50R20 in inches · 275/55R20 in inches · change sizes in the calculator

FAQ

What is the difference between 285/50R20 and 275/55R20?

275/55R20 is 0.69" taller (+2.21%) and 0.39" narrower than 285/50R20.

Will 275/55R20 change my speedometer?

Yes, by +2.21%. When the speedometer shows 60 mph you would be going 61.3 mph.

Can I replace 285/50R20 with 275/55R20?

Often yes: the diameter change of +2.2% is within the common 3% guideline. Check the load index, speed rating and clearance.