Tire Size Box

275/40R16 vs 275/45R16

275/45R16 compared with 275/40R16

+4.4% diameter, 0.0" width

275/45R16 is 25.74" tall vs 24.66". More than the 3% rule of thumb, so check carefully before switching.

24.7"16" rim4.3"10.8" wide
275/40R16 (solid) compared with 275/45R16 (dashed outline), drawn to scale

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

62.6 mph

275/45R16 is +1.08 inches (+4.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/40R16275/45R16Difference%
Overall diameter24.66"25.74"+1.08"+4.4%
Section width10.83"10.83"0.00"0.0%
Sidewall height4.33"4.87"+0.54"+12.5%
Circumference77.48"80.88"+3.40"+4.4%
Revolutions per mile817.8783.4−34.4−4.2%

Speedometer difference

If your vehicle came with 275/40R16 and you fit 275/45R16, 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 mph62.6 mph+2.6 mph
65 mph67.9 mph+2.9 mph
70 mph73.1 mph+3.1 mph
75 mph78.3 mph+3.3 mph
80 mph83.5 mph+3.5 mph

Each size on its own

Questions

Which is bigger, 275/40R16 or 275/45R16?
275/45R16 is taller by 1.08 inches (25.74" vs 24.66"). 275/40R16 is the same width.
Can I replace 275/40R16 with 275/45R16?
It is not recommended without checking carefully. The diameter difference is +4.4%, 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 275/40R16), your real speed is 62.6 mph. Your odometer will under-count miles by about 4.4%.
Will 275/45R16 lift my vehicle?
Ride height changes by half the diameter difference: +0.54 inches of ground clearance at the axle.

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