Tire Size Box

205/60R18 vs 225/60R18

225/60R18 compared with 205/60R18

+3.4% diameter, +0.8" width

225/60R18 is 28.63" 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 225/60R18 (dashed outline), drawn to scale

With 225/60R18 tires, when your speedometer says 60 mph you are really going

62.0 mph

225/60R18 is +0.94 inches (+3.4%) in overall diameter. That is more than the 3% most shops and makers recommend.

205/60R18225/60R18Difference%
Overall diameter27.69"28.63"+0.94"+3.4%
Section width8.07"8.86"+0.79"+9.8%
Sidewall height4.84"5.31"+0.47"+9.8%
Circumference86.98"89.94"+2.97"+3.4%
Revolutions per mile728.5704.4−24.0−3.3%

Speedometer difference

If your vehicle came with 205/60R18 and you fit 225/60R18, 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 mph41.4 mph+1.4 mph
50 mph51.7 mph+1.7 mph
60 mph62.0 mph+2.0 mph
65 mph67.2 mph+2.2 mph
70 mph72.4 mph+2.4 mph
75 mph77.6 mph+2.6 mph
80 mph82.7 mph+2.7 mph

Each size on its own

Questions

Which is bigger, 205/60R18 or 225/60R18?
225/60R18 is taller by 0.94 inches (28.63" vs 27.69"). 225/60R18 is wider by 0.79 inches.
Can I replace 205/60R18 with 225/60R18?
It is not recommended without checking carefully. The diameter difference is +3.4%, 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 225/60R18 change my speedometer?
When your speedometer reads 60 mph with 225/60R18 fitted (calibrated for 205/60R18), your real speed is 62.0 mph. Your odometer will under-count miles by about 3.4%.
Will 225/60R18 lift my vehicle?
Ride height changes by half the diameter difference: +0.47 inches of ground clearance at the axle.

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