Tire Size Box

225/75R13 vs 245/70R13

245/70R13 compared with 225/75R13

+0.8% diameter, +0.8" width

245/70R13 is 26.50" tall vs 26.29". Within the 3% rule, so usually interchangeable.

26.3"13" rim6.6"8.9" wide
225/75R13 (solid) compared with 245/70R13 (dashed outline), drawn to scale

With 245/70R13 tires, when your speedometer says 60 mph you are really going

60.5 mph

245/70R13 is +0.22 inches (+0.8%) in overall diameter. That is within the 3% most shops and makers allow.

225/75R13245/70R13Difference%
Overall diameter26.29"26.50"+0.22"+0.8%
Section width8.86"9.65"+0.79"+8.9%
Sidewall height6.64"6.75"+0.11"+1.6%
Circumference82.58"83.26"+0.68"+0.8%
Revolutions per mile767.2760.9−6.3−0.8%

Speedometer difference

If your vehicle came with 225/75R13 and you fit 245/70R13, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.2 mph+0.2 mph
30 mph30.2 mph+0.2 mph
40 mph40.3 mph+0.3 mph
50 mph50.4 mph+0.4 mph
60 mph60.5 mph+0.5 mph
65 mph65.5 mph+0.5 mph
70 mph70.6 mph+0.6 mph
75 mph75.6 mph+0.6 mph
80 mph80.7 mph+0.7 mph

Each size on its own

Questions

Which is bigger, 225/75R13 or 245/70R13?
245/70R13 is taller by 0.22 inches (26.50" vs 26.29"). 245/70R13 is wider by 0.79 inches.
Can I replace 225/75R13 with 245/70R13?
Usually, yes. The diameter difference is +0.8%, inside the 3% rule of thumb most tire shops use. Check that the wider or taller tire clears your suspension and fenders, and that its load index meets your placard.
How much will 245/70R13 change my speedometer?
When your speedometer reads 60 mph with 245/70R13 fitted (calibrated for 225/75R13), your real speed is 60.5 mph. Your odometer will under-count miles by about 0.8%.
Will 245/70R13 lift my vehicle?
Ride height changes by half the diameter difference: +0.11 inches of ground clearance at the axle.

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