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235/35R20 vs 265/35R20

265/35R20 is outside the ±3% rule as a replacement for 235/35R20: the diameter differs by +3.12%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.

20" rim
235/35R20 26.48" · 265/35R20 27.30" · drawn to scale

Side by side

235/35R20265/35R20Difference
Overall diameter26.48"27.30"+0.83" (+3.12%)
Section width235 mm265 mm+30 mm
Sidewall3.24"3.65"+0.41"
Rim20"20"same
Circumference83.2"85.8"+2.6"
Revs per mile762739-23
Ride height——+0.41"
Speedometer reads 60 mph60.061.9+1.9 mph

Speedometer and odometer

020406080100120 reads 60 · actual 61.9 mph

With 265/35R20 on a car calibrated for 235/35R20, the speedometer reads 58.2 mph when you're really doing 60, and the odometer under-counts by 3.1%.

Speedo showsActual speed
30 mph30.9 mph
45 mph46.4 mph
60 mph61.9 mph
70 mph72.2 mph
80 mph82.5 mph

Other sizes close to 235/35R20

Questions

Can I replace 235/35R20 with 265/35R20?

265/35R20 is outside the ±3% rule as a replacement for 235/35R20: the diameter differs by +3.12%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.

What's the difference between 235/35R20 and 265/35R20?

265/35R20 is 0.83" taller and 30 mm wider; the sidewall is +0.41". At an indicated 60 mph you'd actually be doing 61.9 mph.

Will 265/35R20 fit on 235/35R20 wheels?

Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 265 mm tire and the fender clearance.