305/40R22 vs 275/45R22

Q: Can I replace 305/40R22 with 275/45R22?

275/45R22 is a safe swap for 305/40R22 by the usual ±3% rule: the diameter differs by +0.44%.

275/45R22 is a safe swap for 305/40R22 by the usual ±3% rule: the diameter differs by +0.44%.

305/40R22 31.61" · 275/45R22 31.74" · drawn to scale

Side by side

	305/40R22	275/45R22	Difference
Overall diameter	31.61"	31.74"	+0.14" (+0.44%)
Section width	305 mm	275 mm	-30 mm
Sidewall	4.80"	4.87"	+0.07"
Rim	22"	22"	same
Circumference	99.3"	99.7"	+0.4"
Revs per mile	638	635	-3
Ride height	—	—	+0.07"
Speedometer reads 60 mph	60.0	60.3	+0.3 mph

Speedometer and odometer

With 275/45R22 on a car calibrated for 305/40R22, the speedometer reads 59.7 mph when you're really doing 60, and the odometer under-counts by 0.4%.

Speedo shows	Actual speed
30 mph	30.1 mph
45 mph	45.2 mph
60 mph	60.3 mph
70 mph	70.3 mph
80 mph	80.3 mph

Other sizes close to 305/40R22

Questions

Can I replace 305/40R22 with 275/45R22?

275/45R22 is a safe swap for 305/40R22 by the usual ±3% rule: the diameter differs by +0.44%.

What's the difference between 305/40R22 and 275/45R22?

275/45R22 is 0.14" taller and 30 mm narrower; the sidewall is +0.07". At an indicated 60 mph you'd actually be doing 60.3 mph.

Will 275/45R22 fit on 305/40R22 wheels?

Both use a 22" rim, so the wheel diameter matches; check the wheel's width range for a 275 mm tire and the fender clearance.