CarSpecsHQ

265/40R18 vs 235/40R19

235/40R19 is a safe swap for 265/40R18 by the usual ±3% rule: the diameter differs by +0.21%.

18" → 19"
265/40R18 26.35" · 235/40R19 26.40" · drawn to scale

Side by side

265/40R18235/40R19Difference
Overall diameter26.35"26.40"+0.06" (+0.21%)
Section width265 mm235 mm-30 mm
Sidewall4.17"3.70"-0.47"
Rim18"19"+1"
Circumference82.8"82.9"+0.2"
Revs per mile765764-2
Ride height——+0.03"
Speedometer reads 60 mph60.060.1+0.1 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.1 mph

With 235/40R19 on a car calibrated for 265/40R18, 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 mph70.1 mph
80 mph80.2 mph

Other sizes close to 265/40R18

Questions

Can I replace 265/40R18 with 235/40R19?

235/40R19 is a safe swap for 265/40R18 by the usual ±3% rule: the diameter differs by +0.21%.

What's the difference between 265/40R18 and 235/40R19?

235/40R19 is 0.06" taller and 30 mm narrower; the sidewall is -0.47". At an indicated 60 mph you'd actually be doing 60.1 mph.

Will 235/40R19 fit on 265/40R18 wheels?

No — 265/40R18 needs a 18" wheel and 235/40R19 a 19" wheel. This is a plus/minus-size swap that changes wheels too.