Tire Size Box

205/40R16 vs 205/45R16

205/45R16 compared with 205/40R16

+3.6% diameter, 0.0" width

205/45R16 is 23.26" tall vs 22.46". More than the 3% rule of thumb, so check carefully before switching.

22.5"16" rim3.2"8.1" wide
205/40R16 (solid) compared with 205/45R16 (dashed outline), drawn to scale

With 205/45R16 tires, when your speedometer says 60 mph you are really going

62.2 mph

205/45R16 is +0.81 inches (+3.6%) in overall diameter. That is more than the 3% most shops and makers recommend.

205/40R16205/45R16Difference%
Overall diameter22.46"23.26"+0.81"+3.6%
Section width8.07"8.07"0.00"0.0%
Sidewall height3.23"3.63"+0.40"+12.5%
Circumference70.55"73.09"+2.54"+3.6%
Revolutions per mile898.1866.9−31.2−3.5%

Speedometer difference

If your vehicle came with 205/40R16 and you fit 205/45R16, 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 mph41.4 mph+1.4 mph
50 mph51.8 mph+1.8 mph
60 mph62.2 mph+2.2 mph
65 mph67.3 mph+2.3 mph
70 mph72.5 mph+2.5 mph
75 mph77.7 mph+2.7 mph
80 mph82.9 mph+2.9 mph

Each size on its own

Questions

Which is bigger, 205/40R16 or 205/45R16?
205/45R16 is taller by 0.81 inches (23.26" vs 22.46"). 205/40R16 is the same width.
Can I replace 205/40R16 with 205/45R16?
It is not recommended without checking carefully. The diameter difference is +3.6%, 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 205/45R16 change my speedometer?
When your speedometer reads 60 mph with 205/45R16 fitted (calibrated for 205/40R16), your real speed is 62.2 mph. Your odometer will under-count miles by about 3.6%.
Will 205/45R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.40 inches of ground clearance at the axle.

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