Tire Size Box

195/55R18 vs 195/65R18

195/65R18 compared with 195/55R18

+5.8% diameter, 0.0" width

195/65R18 is 27.98" tall vs 26.44". More than the 3% rule of thumb, so check carefully before switching.

26.4"18" rim4.2"7.7" wide
195/55R18 (solid) compared with 195/65R18 (dashed outline), drawn to scale

With 195/65R18 tires, when your speedometer says 60 mph you are really going

63.5 mph

195/65R18 is +1.54 inches (+5.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

195/55R18195/65R18Difference%
Overall diameter26.44"27.98"+1.54"+5.8%
Section width7.68"7.68"0.00"0.0%
Sidewall height4.22"4.99"+0.77"+18.2%
Circumference83.08"87.90"+4.82"+5.8%
Revolutions per mile762.6720.8−41.9−5.5%

Speedometer difference

If your vehicle came with 195/55R18 and you fit 195/65R18, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph21.2 mph+1.2 mph
30 mph31.7 mph+1.7 mph
40 mph42.3 mph+2.3 mph
50 mph52.9 mph+2.9 mph
60 mph63.5 mph+3.5 mph
65 mph68.8 mph+3.8 mph
70 mph74.1 mph+4.1 mph
75 mph79.4 mph+4.4 mph
80 mph84.6 mph+4.6 mph

Each size on its own

Questions

Which is bigger, 195/55R18 or 195/65R18?
195/65R18 is taller by 1.54 inches (27.98" vs 26.44"). 195/55R18 is the same width.
Can I replace 195/55R18 with 195/65R18?
It is not recommended without checking carefully. The diameter difference is +5.8%, 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 195/65R18 change my speedometer?
When your speedometer reads 60 mph with 195/65R18 fitted (calibrated for 195/55R18), your real speed is 63.5 mph. Your odometer will under-count miles by about 5.8%.
Will 195/65R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.77 inches of ground clearance at the axle.

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