Tire Size Box

305/55R17 vs 285/60R17

285/60R17 compared with 305/55R17

+0.8% diameter, −0.8" width

285/60R17 is 30.46" tall vs 30.21". Within the 3% rule, so usually interchangeable.

30.2"17" rim6.6"12.0" wide
305/55R17 (solid) compared with 285/60R17 (dashed outline), drawn to scale

With 285/60R17 tires, when your speedometer says 60 mph you are really going

60.5 mph

285/60R17 is +0.26 inches (+0.8%) in overall diameter. That is within the 3% most shops and makers allow.

305/55R17285/60R17Difference%
Overall diameter30.21"30.46"+0.26"+0.8%
Section width12.01"11.22"−0.79"−6.6%
Sidewall height6.60"6.73"+0.13"+1.9%
Circumference94.90"95.71"+0.80"+0.8%
Revolutions per mile667.6662.0−5.6−0.8%

Speedometer difference

If your vehicle came with 305/55R17 and you fit 285/60R17, here is your real speed for each speedometer reading:

Speedometer showsActual speedDifference
20 mph20.2 mph+0.2 mph
30 mph30.3 mph+0.3 mph
40 mph40.3 mph+0.3 mph
50 mph50.4 mph+0.4 mph
60 mph60.5 mph+0.5 mph
65 mph65.6 mph+0.6 mph
70 mph70.6 mph+0.6 mph
75 mph75.6 mph+0.6 mph
80 mph80.7 mph+0.7 mph

Each size on its own

Questions

Which is bigger, 305/55R17 or 285/60R17?
285/60R17 is taller by 0.26 inches (30.46" vs 30.21"). 305/55R17 is wider by 0.79 inches.
Can I replace 305/55R17 with 285/60R17?
Usually, yes. The diameter difference is +0.8%, inside the 3% rule of thumb most tire shops use. Check that the wider or taller tire clears your suspension and fenders, and that its load index meets your placard.
How much will 285/60R17 change my speedometer?
When your speedometer reads 60 mph with 285/60R17 fitted (calibrated for 305/55R17), your real speed is 60.5 mph. Your odometer will under-count miles by about 0.8%.
Will 285/60R17 lift my vehicle?
Ride height changes by half the diameter difference: +0.13 inches of ground clearance at the axle.

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