Tire Size Box

225/65R15 vs 245/65R15

245/65R15 compared with 225/65R15

+3.9% diameter, +0.8" width

245/65R15 is 27.54" tall vs 26.52". More than the 3% rule of thumb, so check carefully before switching.

26.5"15" rim5.8"8.9" wide
225/65R15 (solid) compared with 245/65R15 (dashed outline), drawn to scale

With 245/65R15 tires, when your speedometer says 60 mph you are really going

62.3 mph

245/65R15 is +1.02 inches (+3.9%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/65R15245/65R15Difference%
Overall diameter26.52"27.54"+1.02"+3.9%
Section width8.86"9.65"+0.79"+8.9%
Sidewall height5.76"6.27"+0.51"+8.9%
Circumference83.30"86.52"+3.22"+3.9%
Revolutions per mile760.6732.3−28.3−3.7%

Speedometer difference

If your vehicle came with 225/65R15 and you fit 245/65R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.8 mph+0.8 mph
30 mph31.2 mph+1.2 mph
40 mph41.5 mph+1.5 mph
50 mph51.9 mph+1.9 mph
60 mph62.3 mph+2.3 mph
65 mph67.5 mph+2.5 mph
70 mph72.7 mph+2.7 mph
75 mph77.9 mph+2.9 mph
80 mph83.1 mph+3.1 mph

Each size on its own

Questions

Which is bigger, 225/65R15 or 245/65R15?
245/65R15 is taller by 1.02 inches (27.54" vs 26.52"). 245/65R15 is wider by 0.79 inches.
Can I replace 225/65R15 with 245/65R15?
It is not recommended without checking carefully. The diameter difference is +3.9%, 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 245/65R15 change my speedometer?
When your speedometer reads 60 mph with 245/65R15 fitted (calibrated for 225/65R15), your real speed is 62.3 mph. Your odometer will under-count miles by about 3.9%.
Will 245/65R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.51 inches of ground clearance at the axle.

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