Tire Size Box

225/70R15 vs 225/75R15

225/75R15 compared with 225/70R15

+3.2% diameter, 0.0" width

225/75R15 is 28.29" tall vs 27.40". More than the 3% rule of thumb, so check carefully before switching.

27.4"15" rim6.2"8.9" wide
225/70R15 (solid) compared with 225/75R15 (dashed outline), drawn to scale

With 225/75R15 tires, when your speedometer says 60 mph you are really going

61.9 mph

225/75R15 is +0.89 inches (+3.2%) in overall diameter. That is more than the 3% most shops and makers recommend.

225/70R15225/75R15Difference%
Overall diameter27.40"28.29"+0.89"+3.2%
Section width8.86"8.86"0.00"0.0%
Sidewall height6.20"6.64"+0.44"+7.1%
Circumference86.08"88.87"+2.78"+3.2%
Revolutions per mile736.0713.0−23.0−3.1%

Speedometer difference

If your vehicle came with 225/70R15 and you fit 225/75R15, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.6 mph+0.6 mph
30 mph31.0 mph+1.0 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph61.9 mph+1.9 mph
65 mph67.1 mph+2.1 mph
70 mph72.3 mph+2.3 mph
75 mph77.4 mph+2.4 mph
80 mph82.6 mph+2.6 mph

Each size on its own

Questions

Which is bigger, 225/70R15 or 225/75R15?
225/75R15 is taller by 0.89 inches (28.29" vs 27.40"). 225/70R15 is the same width.
Can I replace 225/70R15 with 225/75R15?
It is not recommended without checking carefully. The diameter difference is +3.2%, 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 225/75R15 change my speedometer?
When your speedometer reads 60 mph with 225/75R15 fitted (calibrated for 225/70R15), your real speed is 61.9 mph. Your odometer will under-count miles by about 3.2%.
Will 225/75R15 lift my vehicle?
Ride height changes by half the diameter difference: +0.44 inches of ground clearance at the axle.

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