CarSpecsHQ

255/50R19 vs 235/60R18

235/60R18 is a safe swap for 255/50R19 by the usual ±3% rule: the diameter differs by +0.22%.

19" → 18"
255/50R19 29.04" · 235/60R18 29.10" · drawn to scale

Side by side

255/50R19235/60R18Difference
Overall diameter29.04"29.10"+0.06" (+0.22%)
Section width255 mm235 mm-20 mm
Sidewall5.02"5.55"+0.53"
Rim19"18"-1"
Circumference91.2"91.4"+0.2"
Revs per mile695693-2
Ride height——+0.03"
Speedometer reads 60 mph60.060.1+0.1 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.1 mph

With 235/60R18 on a car calibrated for 255/50R19, the speedometer reads 59.9 mph when you're really doing 60, and the odometer under-counts by 0.2%.

Speedo showsActual speed
30 mph30.1 mph
45 mph45.1 mph
60 mph60.1 mph
70 mph70.2 mph
80 mph80.2 mph

Other sizes close to 255/50R19

Questions

Can I replace 255/50R19 with 235/60R18?

235/60R18 is a safe swap for 255/50R19 by the usual ±3% rule: the diameter differs by +0.22%.

What's the difference between 255/50R19 and 235/60R18?

235/60R18 is 0.06" taller and 20 mm narrower; the sidewall is +0.53". At an indicated 60 mph you'd actually be doing 60.1 mph.

Will 235/60R18 fit on 255/50R19 wheels?

No — 255/50R19 needs a 19" wheel and 235/60R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.