Tire Size Box

285/40R16 vs 275/45R16

275/45R16 compared with 285/40R16

+3.1% diameter, −0.4" width

275/45R16 is 25.74" 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 275/45R16 (dashed outline), drawn to scale

With 275/45R16 tires, when your speedometer says 60 mph you are really going

61.8 mph

275/45R16 is +0.77 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

285/40R16275/45R16Difference%
Overall diameter24.98"25.74"+0.77"+3.1%
Section width11.22"10.83"−0.39"−3.5%
Sidewall height4.49"4.87"+0.38"+8.6%
Circumference78.47"80.88"+2.41"+3.1%
Revolutions per mile807.5783.4−24.1−3.0%

Speedometer difference

If your vehicle came with 285/40R16 and you fit 275/45R16, 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 mph72.2 mph+2.2 mph
75 mph77.3 mph+2.3 mph
80 mph82.5 mph+2.5 mph

Each size on its own

Questions

Which is bigger, 285/40R16 or 275/45R16?
275/45R16 is taller by 0.77 inches (25.74" vs 24.98"). 285/40R16 is wider by 0.39 inches.
Can I replace 285/40R16 with 275/45R16?
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 275/45R16 change my speedometer?
When your speedometer reads 60 mph with 275/45R16 fitted (calibrated for 285/40R16), your real speed is 61.8 mph. Your odometer will under-count miles by about 3.1%.
Will 275/45R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.38 inches of ground clearance at the axle.

Other comparisons