Tire Size Box

225/75R15 vs 225/80R15

225/80R15 compared with 225/75R15

+3.1% diameter, 0.0" width

225/80R15 is 29.17" tall vs 28.29". More than the 3% rule of thumb, so check carefully before switching.

28.3"15" rim6.6"8.9" wide
225/75R15 (solid) compared with 225/80R15 (dashed outline), drawn to scale

With 225/80R15 tires, when your speedometer says 60 mph you are really going

61.9 mph

225/80R15 is +0.89 inches (+3.1%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/75R15225/80R15Difference%
Overall diameter28.29"29.17"+0.89"+3.1%
Section width8.86"8.86"0.00"0.0%
Sidewall height6.64"7.09"+0.44"+6.7%
Circumference88.87"91.65"+2.78"+3.1%
Revolutions per mile713.0691.3−21.6−3.0%

Speedometer difference

If your vehicle came with 225/75R15 and you fit 225/80R15, 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 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 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, 225/75R15 or 225/80R15?
225/80R15 is taller by 0.89 inches (29.17" vs 28.29"). 225/75R15 is the same width.
Can I replace 225/75R15 with 225/80R15?
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 225/80R15 change my speedometer?
When your speedometer reads 60 mph with 225/80R15 fitted (calibrated for 225/75R15), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.1%.
Will 225/80R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.44 inches of ground clearance at the axle.

Other comparisons