245/75R17 vs 265/65R18

Q: Can I replace 245/75R17 with 265/65R18?

265/65R18 is a safe swap for 245/75R17 by the usual ±3% rule: the diameter differs by +0.30%.

265/65R18 is a safe swap for 245/75R17 by the usual ±3% rule: the diameter differs by +0.30%.

245/75R17 31.47" · 265/65R18 31.56" · drawn to scale

Side by side

	245/75R17	265/65R18	Difference
Overall diameter	31.47"	31.56"	+0.09" (+0.30%)
Section width	245 mm	265 mm	+20 mm
Sidewall	7.23"	6.78"	-0.45"
Rim	17"	18"	+1"
Circumference	98.9"	99.2"	+0.3"
Revs per mile	641	639	-2
Ride height	—	—	+0.05"
Speedometer reads 60 mph	60.0	60.2	+0.2 mph

Speedometer and odometer

With 265/65R18 on a car calibrated for 245/75R17, the speedometer reads 59.8 mph when you're really doing 60, and the odometer under-counts by 0.3%.

Speedo shows	Actual speed
30 mph	30.1 mph
45 mph	45.1 mph
60 mph	60.2 mph
70 mph	70.2 mph
80 mph	80.2 mph

Other sizes close to 245/75R17

Questions

Can I replace 245/75R17 with 265/65R18?

265/65R18 is a safe swap for 245/75R17 by the usual ±3% rule: the diameter differs by +0.30%.

What's the difference between 245/75R17 and 265/65R18?

265/65R18 is 0.09" taller and 20 mm wider; the sidewall is -0.45". At an indicated 60 mph you'd actually be doing 60.2 mph.

Will 265/65R18 fit on 245/75R17 wheels?

No — 245/75R17 needs a 17" wheel and 265/65R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.