255/60R19 vs 285/50R20

Q: Can I replace 255/60R19 with 285/50R20?

285/50R20 is a safe swap for 255/60R19 by the usual ±3% rule: the diameter differs by +0.56%.

285/50R20 is a safe swap for 255/60R19 by the usual ±3% rule: the diameter differs by +0.56%.

255/60R19 31.05" · 285/50R20 31.22" · drawn to scale

Side by side

	255/60R19	285/50R20	Difference
Overall diameter	31.05"	31.22"	+0.17" (+0.56%)
Section width	255 mm	285 mm	+30 mm
Sidewall	6.02"	5.61"	-0.41"
Rim	19"	20"	+1"
Circumference	97.5"	98.1"	+0.5"
Revs per mile	650	646	-4
Ride height	—	—	+0.09"
Speedometer reads 60 mph	60.0	60.3	+0.3 mph

Speedometer and odometer

With 285/50R20 on a car calibrated for 255/60R19, the speedometer reads 59.7 mph when you're really doing 60, and the odometer under-counts by 0.6%.

Speedo shows	Actual speed
30 mph	30.2 mph
45 mph	45.3 mph
60 mph	60.3 mph
70 mph	70.4 mph
80 mph	80.4 mph

Other sizes close to 255/60R19

Questions

Can I replace 255/60R19 with 285/50R20?

285/50R20 is a safe swap for 255/60R19 by the usual ±3% rule: the diameter differs by +0.56%.

What's the difference between 255/60R19 and 285/50R20?

285/50R20 is 0.17" taller and 30 mm wider; the sidewall is -0.41". At an indicated 60 mph you'd actually be doing 60.3 mph.

Will 285/50R20 fit on 255/60R19 wheels?

No — 255/60R19 needs a 19" wheel and 285/50R20 a 20" wheel. This is a plus/minus-size swap that changes wheels too.