CarSpecsHQ

235/75R17 vs 255/70R17

255/70R17 is a safe swap for 235/75R17 by the usual ±3% rule: the diameter differs by +0.57%.

17" rim
235/75R17 30.88" · 255/70R17 31.06" · drawn to scale

Side by side

235/75R17255/70R17Difference
Overall diameter30.88"31.06"+0.18" (+0.57%)
Section width235 mm255 mm+20 mm
Sidewall6.94"7.03"+0.09"
Rim17"17"same
Circumference97.0"97.6"+0.6"
Revs per mile653649-4
Ride height——+0.09"
Speedometer reads 60 mph60.060.3+0.3 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.3 mph

With 255/70R17 on a car calibrated for 235/75R17, the speedometer reads 59.7 mph when you're really doing 60, and the odometer under-counts by 0.6%.

Speedo showsActual speed
30 mph30.2 mph
45 mph45.3 mph
60 mph60.3 mph
70 mph70.4 mph
80 mph80.5 mph

Other sizes close to 235/75R17

Questions

Can I replace 235/75R17 with 255/70R17?

255/70R17 is a safe swap for 235/75R17 by the usual ±3% rule: the diameter differs by +0.57%.

What's the difference between 235/75R17 and 255/70R17?

255/70R17 is 0.18" taller and 20 mm wider; the sidewall is +0.09". At an indicated 60 mph you'd actually be doing 60.3 mph.

Will 255/70R17 fit on 235/75R17 wheels?

Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.