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255/35R20 vs 295/35R20

295/35R20 is outside the ±3% rule as a replacement for 255/35R20: the diameter differs by +4.08%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.

20" rim
255/35R20 27.03" · 295/35R20 28.13" · drawn to scale

Side by side

255/35R20295/35R20Difference
Overall diameter27.03"28.13"+1.10" (+4.08%)
Section width255 mm295 mm+40 mm
Sidewall3.51"4.06"+0.55"
Rim20"20"same
Circumference84.9"88.4"+3.5"
Revs per mile746717-29
Ride height——+0.55"
Speedometer reads 60 mph60.062.4+2.4 mph

Speedometer and odometer

020406080100120 reads 60 · actual 62.4 mph

With 295/35R20 on a car calibrated for 255/35R20, the speedometer reads 57.6 mph when you're really doing 60, and the odometer under-counts by 4.1%.

Speedo showsActual speed
30 mph31.2 mph
45 mph46.8 mph
60 mph62.4 mph
70 mph72.9 mph
80 mph83.3 mph

Other sizes close to 255/35R20

Questions

Can I replace 255/35R20 with 295/35R20?

295/35R20 is outside the ±3% rule as a replacement for 255/35R20: the diameter differs by +4.08%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.

What's the difference between 255/35R20 and 295/35R20?

295/35R20 is 1.10" taller and 40 mm wider; the sidewall is +0.55". At an indicated 60 mph you'd actually be doing 62.4 mph.

Will 295/35R20 fit on 255/35R20 wheels?

Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 295 mm tire and the fender clearance.