Tire Size Box

245/65R17 vs 245/70R17

245/70R17 compared with 245/65R17

+3.3% diameter, 0.0" width

245/70R17 is 30.50" tall vs 29.54". More than the 3% rule of thumb, so check carefully before switching.

29.5"17" rim6.3"9.6" wide
245/65R17 (solid) compared with 245/70R17 (dashed outline), drawn to scale

With 245/70R17 tires, when your speedometer says 60 mph you are really going

62.0 mph

245/70R17 is +0.96 inches (+3.3%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/65R17245/70R17Difference%
Overall diameter29.54"30.50"+0.96"+3.3%
Section width9.65"9.65"0.00"0.0%
Sidewall height6.27"6.75"+0.48"+7.7%
Circumference92.80"95.83"+3.03"+3.3%
Revolutions per mile682.8661.2−21.6−3.2%

Speedometer difference

If your vehicle came with 245/65R17 and you fit 245/70R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.7 mph+0.7 mph
30 mph31.0 mph+1.0 mph
40 mph41.3 mph+1.3 mph
50 mph51.6 mph+1.6 mph
60 mph62.0 mph+2.0 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, 245/65R17 or 245/70R17?
245/70R17 is taller by 0.96 inches (30.50" vs 29.54"). 245/65R17 is the same width.
Can I replace 245/65R17 with 245/70R17?
It is not recommended without checking carefully. The diameter difference is +3.3%, 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 245/70R17 change my speedometer?
When your speedometer reads 60 mph with 245/70R17 fitted (calibrated for 245/65R17), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.3%.
Will 245/70R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.48 inches of ground clearance at the axle.

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