Tire Size Box

285/40R16 vs 285/45R16

285/45R16 compared with 285/40R16

+4.5% diameter, 0.0" width

285/45R16 is 26.10" tall vs 24.98". More than the 3% rule of thumb, so check carefully before switching.

25.0"16" rim4.5"11.2" wide
285/40R16 (solid) compared with 285/45R16 (dashed outline), drawn to scale

With 285/45R16 tires, when your speedometer says 60 mph you are really going

62.7 mph

285/45R16 is +1.12 inches (+4.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

285/40R16285/45R16Difference%
Overall diameter24.98"26.10"+1.12"+4.5%
Section width11.22"11.22"0.00"0.0%
Sidewall height4.49"5.05"+0.56"+12.5%
Circumference78.47"81.99"+3.53"+4.5%
Revolutions per mile807.5772.8−34.7−4.3%

Speedometer difference

If your vehicle came with 285/40R16 and you fit 285/45R16, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.9 mph+0.9 mph
30 mph31.3 mph+1.3 mph
40 mph41.8 mph+1.8 mph
50 mph52.2 mph+2.2 mph
60 mph62.7 mph+2.7 mph
65 mph67.9 mph+2.9 mph
70 mph73.1 mph+3.1 mph
75 mph78.4 mph+3.4 mph
80 mph83.6 mph+3.6 mph

Each size on its own

Questions

Which is bigger, 285/40R16 or 285/45R16?
285/45R16 is taller by 1.12 inches (26.10" vs 24.98"). 285/40R16 is the same width.
Can I replace 285/40R16 with 285/45R16?
It is not recommended without checking carefully. The diameter difference is +4.5%, 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 285/45R16 change my speedometer?
When your speedometer reads 60 mph with 285/45R16 fitted (calibrated for 285/40R16), your real speed is 62.7 mph. Your odometer will under-count miles by about 4.5%.
Will 285/45R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.56 inches of ground clearance at the axle.

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