245/45R20 vs 265/45R20

Q: Can I replace 245/45R20 with 265/45R20?

265/45R20 is a safe swap for 245/45R20 by the usual ±3% rule: the diameter differs by +2.47%.

265/45R20 is a safe swap for 245/45R20 by the usual ±3% rule: the diameter differs by +2.47%.

245/45R20 28.68" · 265/45R20 29.39" · drawn to scale

Side by side

	245/45R20	265/45R20	Difference
Overall diameter	28.68"	29.39"	+0.71" (+2.47%)
Section width	245 mm	265 mm	+20 mm
Sidewall	4.34"	4.69"	+0.35"
Rim	20"	20"	same
Circumference	90.1"	92.3"	+2.2"
Revs per mile	703	686	-17
Ride height	—	—	+0.35"
Speedometer reads 60 mph	60.0	61.5	+1.5 mph

Speedometer and odometer

With 265/45R20 on a car calibrated for 245/45R20, the speedometer reads 58.6 mph when you're really doing 60, and the odometer under-counts by 2.5%.

Speedo shows	Actual speed
30 mph	30.7 mph
45 mph	46.1 mph
60 mph	61.5 mph
70 mph	71.7 mph
80 mph	82.0 mph

Other sizes close to 245/45R20

Questions

Can I replace 245/45R20 with 265/45R20?

265/45R20 is a safe swap for 245/45R20 by the usual ±3% rule: the diameter differs by +2.47%.

What's the difference between 245/45R20 and 265/45R20?

265/45R20 is 0.71" taller and 20 mm wider; the sidewall is +0.35". At an indicated 60 mph you'd actually be doing 61.5 mph.

Will 265/45R20 fit on 245/45R20 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.