275/55R19 vs 285/50R20

Q: Can I replace 275/55R19 with 285/50R20?

285/50R20 is a safe swap for 275/55R19 by the usual ±3% rule: the diameter differs by +1.01%.

285/50R20 is a safe swap for 275/55R19 by the usual ±3% rule: the diameter differs by +1.01%.

275/55R19 30.91" · 285/50R20 31.22" · drawn to scale

Side by side

	275/55R19	285/50R20	Difference
Overall diameter	30.91"	31.22"	+0.31" (+1.01%)
Section width	275 mm	285 mm	+10 mm
Sidewall	5.95"	5.61"	-0.34"
Rim	19"	20"	+1"
Circumference	97.1"	98.1"	+1.0"
Revs per mile	652	646	-7
Ride height	—	—	+0.16"
Speedometer reads 60 mph	60.0	60.6	+0.6 mph

Speedometer and odometer

With 285/50R20 on a car calibrated for 275/55R19, the speedometer reads 59.4 mph when you're really doing 60, and the odometer under-counts by 1.0%.

Speedo shows	Actual speed
30 mph	30.3 mph
45 mph	45.5 mph
60 mph	60.6 mph
70 mph	70.7 mph
80 mph	80.8 mph

Other sizes close to 275/55R19

Questions

Can I replace 275/55R19 with 285/50R20?

285/50R20 is a safe swap for 275/55R19 by the usual ±3% rule: the diameter differs by +1.01%.

What's the difference between 275/55R19 and 285/50R20?

285/50R20 is 0.31" taller and 10 mm wider; the sidewall is -0.34". At an indicated 60 mph you'd actually be doing 60.6 mph.

Will 285/50R20 fit on 275/55R19 wheels?

No — 275/55R19 needs a 19" wheel and 285/50R20 a 20" wheel. This is a plus/minus-size swap that changes wheels too.