Tire Size Box

295/40R17 vs 285/45R17

285/45R17 compared with 295/40R17

+3.1% diameter, −0.4" width

285/45R17 is 27.10" tall vs 26.29". More than the 3% rule of thumb, so check carefully before switching.

26.3"17" rim4.6"11.6" wide
295/40R17 (solid) compared with 285/45R17 (dashed outline), drawn to scale

With 285/45R17 tires, when your speedometer says 60 mph you are really going

61.8 mph

285/45R17 is +0.81 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

295/40R17285/45R17Difference%
Overall diameter26.29"27.10"+0.81"+3.1%
Section width11.61"11.22"−0.39"−3.4%
Sidewall height4.65"5.05"+0.40"+8.7%
Circumference82.60"85.13"+2.54"+3.1%
Revolutions per mile767.1744.3−22.8−3.0%

Speedometer difference

If your vehicle came with 295/40R17 and you fit 285/45R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph30.9 mph+0.9 mph
40 mph41.2 mph+1.2 mph
50 mph51.5 mph+1.5 mph
60 mph61.8 mph+1.8 mph
65 mph67.0 mph+2.0 mph
70 mph72.1 mph+2.1 mph
75 mph77.3 mph+2.3 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 295/40R17 or 285/45R17?
285/45R17 is taller by 0.81 inches (27.10" vs 26.29"). 295/40R17 is wider by 0.39 inches.
Can I replace 295/40R17 with 285/45R17?
It is not recommended without checking carefully. The diameter difference is +3.1%, 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 285/45R17 change my speedometer?
When your speedometer reads 60 mph with 285/45R17 fitted (calibrated for 295/40R17), your real speed is 61.8 mph. Your odometer will under-count miles by about 3.1%.
Will 285/45R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.40 inches of ground clearance at the axle.

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