Tire Size Box

245/55R17 vs 245/65R17

245/65R17 compared with 245/55R17

+7.0% diameter, 0.0" width

245/65R17 is 29.54" tall vs 27.61". More than the 3% rule of thumb, so check carefully before switching.

27.6"17" rim5.3"9.6" wide
245/55R17 (solid) compared with 245/65R17 (dashed outline), drawn to scale

With 245/65R17 tires, when your speedometer says 60 mph you are really going

64.2 mph

245/65R17 is +1.93 inches (+7.0%) in overall diameter. That is more than the 3% most shops and makers recommend.

245/55R17245/65R17Difference%
Overall diameter27.61"29.54"+1.93"+7.0%
Section width9.65"9.65"0.00"0.0%
Sidewall height5.31"6.27"+0.96"+18.2%
Circumference86.74"92.80"+6.06"+7.0%
Revolutions per mile730.5682.8−47.7−6.5%

Speedometer difference

If your vehicle came with 245/55R17 and you fit 245/65R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.4 mph+1.4 mph
30 mph32.1 mph+2.1 mph
40 mph42.8 mph+2.8 mph
50 mph53.5 mph+3.5 mph
60 mph64.2 mph+4.2 mph
65 mph69.5 mph+4.5 mph
70 mph74.9 mph+4.9 mph
75 mph80.2 mph+5.2 mph
80 mph85.6 mph+5.6 mph

Each size on its own

Questions

Which is bigger, 245/55R17 or 245/65R17?
245/65R17 is taller by 1.93 inches (29.54" vs 27.61"). 245/55R17 is the same width.
Can I replace 245/55R17 with 245/65R17?
It is not recommended without checking carefully. The diameter difference is +7.0%, 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 245/65R17 change my speedometer?
When your speedometer reads 60 mph with 245/65R17 fitted (calibrated for 245/55R17), your real speed is 64.2 mph. Your odometer will under-count miles by about 7.0%.
Will 245/65R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.96 inches of ground clearance at the axle.

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