235/45R19 vs 255/45R19

Q: Can I replace 235/45R19 with 255/45R19?

255/45R19 is a safe swap for 235/45R19 by the usual ±3% rule: the diameter differs by +2.59%.

255/45R19 is a safe swap for 235/45R19 by the usual ±3% rule: the diameter differs by +2.59%.

235/45R19 27.33" · 255/45R19 28.04" · drawn to scale

Side by side

	235/45R19	255/45R19	Difference
Overall diameter	27.33"	28.04"	+0.71" (+2.59%)
Section width	235 mm	255 mm	+20 mm
Sidewall	4.16"	4.52"	+0.35"
Rim	19"	19"	same
Circumference	85.8"	88.1"	+2.2"
Revs per mile	738	719	-19
Ride height	—	—	+0.35"
Speedometer reads 60 mph	60.0	61.6	+1.6 mph

Speedometer and odometer

With 255/45R19 on a car calibrated for 235/45R19, the speedometer reads 58.5 mph when you're really doing 60, and the odometer under-counts by 2.6%.

Speedo shows	Actual speed
30 mph	30.8 mph
45 mph	46.2 mph
60 mph	61.6 mph
70 mph	71.8 mph
80 mph	82.1 mph

Other sizes close to 235/45R19

Questions

Can I replace 235/45R19 with 255/45R19?

255/45R19 is a safe swap for 235/45R19 by the usual ±3% rule: the diameter differs by +2.59%.

What's the difference between 235/45R19 and 255/45R19?

255/45R19 is 0.71" taller and 20 mm wider; the sidewall is +0.35". At an indicated 60 mph you'd actually be doing 61.6 mph.

Will 255/45R19 fit on 235/45R19 wheels?

Both use a 19" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.