Tire Size Box

215/40R16 vs 215/45R16

215/45R16 compared with 215/40R16

+3.7% diameter, 0.0" width

215/45R16 is 23.62" tall vs 22.77". More than the 3% rule of thumb, so check carefully before switching.

22.8"16" rim3.4"8.5" wide
215/40R16 (solid) compared with 215/45R16 (dashed outline), drawn to scale

With 215/45R16 tires, when your speedometer says 60 mph you are really going

62.2 mph

215/45R16 is +0.85 inches (+3.7%) in overall diameter. That is more than the 3% most shops and makers recommend.

215/40R16215/45R16Difference%
Overall diameter22.77"23.62"+0.85"+3.7%
Section width8.46"8.46"0.00"0.0%
Sidewall height3.39"3.81"+0.42"+12.5%
Circumference71.54"74.20"+2.66"+3.7%
Revolutions per mile885.7853.9−31.7−3.6%

Speedometer difference

If your vehicle came with 215/40R16 and you fit 215/45R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.1 mph+1.1 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.2 mph+2.2 mph
65 mph67.4 mph+2.4 mph
70 mph72.6 mph+2.6 mph
75 mph77.8 mph+2.8 mph
80 mph83.0 mph+3.0 mph

Each size on its own

Questions

Which is bigger, 215/40R16 or 215/45R16?
215/45R16 is taller by 0.85 inches (23.62" vs 22.77"). 215/40R16 is the same width.
Can I replace 215/40R16 with 215/45R16?
It is not recommended without checking carefully. The diameter difference is +3.7%, more than the 3% most shops and makers allow. It will throw off the speedometer and may affect ABS, stability control and clearance.
How much will 215/45R16 change my speedometer?
When your speedometer reads 60 mph with 215/45R16 fitted (calibrated for 215/40R16), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.7%.
Will 215/45R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.42 inches of ground clearance at the axle.

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