Tire Size Box

275/75R15 vs 275/80R15

275/80R15 compared with 275/75R15

+3.5% diameter, 0.0" width

275/80R15 is 32.32" tall vs 31.24". More than the 3% rule of thumb, so check carefully before switching.

31.2"15" rim8.1"10.8" wide
275/75R15 (solid) compared with 275/80R15 (dashed outline), drawn to scale

With 275/80R15 tires, when your speedometer says 60 mph you are really going

62.1 mph

275/80R15 is +1.08 inches (+3.5%) in overall diameter. That is more than the 3% most shops and makers recommend.

275/75R15275/80R15Difference%
Overall diameter31.24"32.32"+1.08"+3.5%
Section width10.83"10.83"0.00"0.0%
Sidewall height8.12"8.66"+0.54"+6.7%
Circumference98.14"101.55"+3.40"+3.5%
Revolutions per mile645.6624.0−21.6−3.3%

Speedometer difference

If your vehicle came with 275/75R15 and you fit 275/80R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.1 mph+2.1 mph
65 mph67.3 mph+2.3 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.8 mph+2.8 mph

Each size on its own

Questions

Which is bigger, 275/75R15 or 275/80R15?
275/80R15 is taller by 1.08 inches (32.32" vs 31.24"). 275/75R15 is the same width.
Can I replace 275/75R15 with 275/80R15?
It is not recommended without checking carefully. The diameter difference is +3.5%, 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 275/80R15 change my speedometer?
When your speedometer reads 60 mph with 275/80R15 fitted (calibrated for 275/75R15), your real speed is 62.1 mph. Your odometer will under-count miles by about 3.5%.
Will 275/80R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.54 inches of ground clearance at the axle.

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