CarSpecsHQ

265/65R18 vs 235/80R17

235/80R17 is a safe swap for 265/65R18 by the usual ±3% rule: the diameter differs by +0.76%.

18" → 17"
265/65R18 31.56" · 235/80R17 31.80" · drawn to scale

Side by side

265/65R18235/80R17Difference
Overall diameter31.56"31.80"+0.24" (+0.76%)
Section width265 mm235 mm-30 mm
Sidewall6.78"7.40"+0.62"
Rim18"17"-1"
Circumference99.2"99.9"+0.8"
Revs per mile639634-5
Ride height——+0.12"
Speedometer reads 60 mph60.060.5+0.5 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.5 mph

With 235/80R17 on a car calibrated for 265/65R18, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.8%.

Speedo showsActual speed
30 mph30.2 mph
45 mph45.3 mph
60 mph60.5 mph
70 mph70.5 mph
80 mph80.6 mph

Other sizes close to 265/65R18

Questions

Can I replace 265/65R18 with 235/80R17?

235/80R17 is a safe swap for 265/65R18 by the usual ±3% rule: the diameter differs by +0.76%.

What's the difference between 265/65R18 and 235/80R17?

235/80R17 is 0.24" taller and 30 mm narrower; the sidewall is +0.62". At an indicated 60 mph you'd actually be doing 60.5 mph.

Will 235/80R17 fit on 265/65R18 wheels?

No — 265/65R18 needs a 18" wheel and 235/80R17 a 17" wheel. This is a plus/minus-size swap that changes wheels too.