275/70R17 vs 255/80R17

Q: Can I replace 275/70R17 with 255/80R17?

255/80R17 is a safe swap for 275/70R17 by the usual ±3% rule: the diameter differs by +2.82%.

255/80R17 is a safe swap for 275/70R17 by the usual ±3% rule: the diameter differs by +2.82%.

275/70R17 32.16" · 255/80R17 33.06" · drawn to scale

Side by side

	275/70R17	255/80R17	Difference
Overall diameter	32.16"	33.06"	+0.91" (+2.82%)
Section width	275 mm	255 mm	-20 mm
Sidewall	7.58"	8.03"	+0.45"
Rim	17"	17"	same
Circumference	101.0"	103.9"	+2.8"
Revs per mile	627	610	-17
Ride height	—	—	+0.45"
Speedometer reads 60 mph	60.0	61.7	+1.7 mph

Speedometer and odometer

With 255/80R17 on a car calibrated for 275/70R17, the speedometer reads 58.4 mph when you're really doing 60, and the odometer under-counts by 2.8%.

Speedo shows	Actual speed
30 mph	30.8 mph
45 mph	46.3 mph
60 mph	61.7 mph
70 mph	72.0 mph
80 mph	82.3 mph

Other sizes close to 275/70R17

Questions

Can I replace 275/70R17 with 255/80R17?

255/80R17 is a safe swap for 275/70R17 by the usual ±3% rule: the diameter differs by +2.82%.

What's the difference between 275/70R17 and 255/80R17?

255/80R17 is 0.91" taller and 20 mm narrower; the sidewall is +0.45". At an indicated 60 mph you'd actually be doing 61.7 mph.

Will 255/80R17 fit on 275/70R17 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.