Tire Size Box

225/80R15 vs 245/80R15

245/80R15 compared with 225/80R15

+4.3% diameter, +0.8" width

245/80R15 is 30.43" tall vs 29.17". More than the 3% rule of thumb, so check carefully before switching.

29.2"15" rim7.1"8.9" wide
225/80R15 (solid) compared with 245/80R15 (dashed outline), drawn to scale

With 245/80R15 tires, when your speedometer says 60 mph you are really going

62.6 mph

245/80R15 is +1.26 inches (+4.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/80R15245/80R15Difference%
Overall diameter29.17"30.43"+1.26"+4.3%
Section width8.86"9.65"+0.79"+8.9%
Sidewall height7.09"7.72"+0.63"+8.9%
Circumference91.65"95.61"+3.96"+4.3%
Revolutions per mile691.3662.7−28.6−4.1%

Speedometer difference

If your vehicle came with 225/80R15 and you fit 245/80R15, 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 mph41.7 mph+1.7 mph
50 mph52.2 mph+2.2 mph
60 mph62.6 mph+2.6 mph
65 mph67.8 mph+2.8 mph
70 mph73.0 mph+3.0 mph
75 mph78.2 mph+3.2 mph
80 mph83.5 mph+3.5 mph

Each size on its own

Questions

Which is bigger, 225/80R15 or 245/80R15?
245/80R15 is taller by 1.26 inches (30.43" vs 29.17"). 245/80R15 is wider by 0.79 inches.
Can I replace 225/80R15 with 245/80R15?
It is not recommended without checking carefully. The diameter difference is +4.3%, 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 245/80R15 change my speedometer?
When your speedometer reads 60 mph with 245/80R15 fitted (calibrated for 225/80R15), your real speed is 62.6 mph. Your odometer will under-count miles by about 4.3%.
Will 245/80R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.63 inches of ground clearance at the axle.

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