CarSpecsHQ

265/35R18 vs 235/45R17

235/45R17 is a safe swap for 265/35R18 by the usual ±3% rule: the diameter differs by +0.09%.

18" → 17"
265/35R18 25.30" · 235/45R17 25.33" · drawn to scale

Side by side

265/35R18235/45R17Difference
Overall diameter25.30"25.33"+0.02" (+0.09%)
Section width265 mm235 mm-30 mm
Sidewall3.65"4.16"+0.51"
Rim18"17"-1"
Circumference79.5"79.6"+0.1"
Revs per mile797796-1
Ride height——+0.01"
Speedometer reads 60 mph60.060.1+0.1 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.1 mph

With 235/45R17 on a car calibrated for 265/35R18, the speedometer reads 59.9 mph when you're really doing 60, and the odometer under-counts by 0.1%.

Speedo showsActual speed
30 mph30.0 mph
45 mph45.0 mph
60 mph60.1 mph
70 mph70.1 mph
80 mph80.1 mph

Other sizes close to 265/35R18

Questions

Can I replace 265/35R18 with 235/45R17?

235/45R17 is a safe swap for 265/35R18 by the usual ±3% rule: the diameter differs by +0.09%.

What's the difference between 265/35R18 and 235/45R17?

235/45R17 is 0.02" taller and 30 mm narrower; the sidewall is +0.51". At an indicated 60 mph you'd actually be doing 60.1 mph.

Will 235/45R17 fit on 265/35R18 wheels?

No — 265/35R18 needs a 18" wheel and 235/45R17 a 17" wheel. This is a plus/minus-size swap that changes wheels too.