Tire Size Box

205/60R18 vs 205/70R18

205/70R18 compared with 205/60R18

+5.8% diameter, 0.0" width

205/70R18 is 29.30" tall vs 27.69". More than the 3% rule of thumb, so check carefully before switching.

27.7"18" rim4.8"8.1" wide
205/60R18 (solid) compared with 205/70R18 (dashed outline), drawn to scale

With 205/70R18 tires, when your speedometer says 60 mph you are really going

63.5 mph

205/70R18 is +1.61 inches (+5.8%) in overall diameter. That is more than the 3% most shops and makers recommend.

205/60R18205/70R18Difference%
Overall diameter27.69"29.30"+1.61"+5.8%
Section width8.07"8.07"0.00"0.0%
Sidewall height4.84"5.65"+0.81"+16.7%
Circumference86.98"92.05"+5.07"+5.8%
Revolutions per mile728.5688.4−40.1−5.5%

Speedometer difference

If your vehicle came with 205/60R18 and you fit 205/70R18, 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 mph84.7 mph+4.7 mph

Each size on its own

Questions

Which is bigger, 205/60R18 or 205/70R18?
205/70R18 is taller by 1.61 inches (29.30" vs 27.69"). 205/60R18 is the same width.
Can I replace 205/60R18 with 205/70R18?
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 205/70R18 change my speedometer?
When your speedometer reads 60 mph with 205/70R18 fitted (calibrated for 205/60R18), your real speed is 63.5 mph. Your odometer will under-count miles by about 5.8%.
Will 205/70R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.81 inches of ground clearance at the axle.

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