235/40R17 vs 215/45R17

Q: Can I replace 235/40R17 with 215/45R17?

215/45R17 is a safe swap for 235/40R17 by the usual ±3% rule: the diameter differs by +0.89%.

215/45R17 is a safe swap for 235/40R17 by the usual ±3% rule: the diameter differs by +0.89%.

235/40R17 24.40" · 215/45R17 24.62" · drawn to scale

Side by side

	235/40R17	215/45R17	Difference
Overall diameter	24.40"	24.62"	+0.22" (+0.89%)
Section width	235 mm	215 mm	-20 mm
Sidewall	3.70"	3.81"	+0.11"
Rim	17"	17"	same
Circumference	76.7"	77.3"	+0.7"
Revs per mile	827	819	-7
Ride height	—	—	+0.11"
Speedometer reads 60 mph	60.0	60.5	+0.5 mph

Speedometer and odometer

With 215/45R17 on a car calibrated for 235/40R17, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.9%.

Speedo shows	Actual speed
30 mph	30.3 mph
45 mph	45.4 mph
60 mph	60.5 mph
70 mph	70.6 mph
80 mph	80.7 mph

Other sizes close to 235/40R17

Questions

Can I replace 235/40R17 with 215/45R17?

215/45R17 is a safe swap for 235/40R17 by the usual ±3% rule: the diameter differs by +0.89%.

What's the difference between 235/40R17 and 215/45R17?

215/45R17 is 0.22" taller and 20 mm narrower; the sidewall is +0.11". At an indicated 60 mph you'd actually be doing 60.5 mph.

Will 215/45R17 fit on 235/40R17 wheels?

Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 215 mm tire and the fender clearance.