285/60R18 vs 285/70R17

285/70R17 is 1.2" taller than 285/60R18 (4.0%)

Diameter difference+3.95%diameter 31.46" → 32.71"
285/60R18285/70R17
285/60R18285/70R17Difference
Overall diameter31.46"32.71"+1.24"
Section width11.22"11.22"±0.00"
Sidewall height6.73"7.85"+1.12"
Circumference98.8"102.8"+3.9"
Revolutions per mile641617−24
Wheel diameter18"17"−1"

Speedometer

ShowsActualDiff
30 mph31.2 mph+1.2
45 mph46.8 mph+1.8
60 mph62.4 mph+2.4
70 mph72.8 mph+2.8
80 mph83.2 mph+3.2

Gear ratio to match

CurrentEquivalent
3.423.56
3.553.69
3.733.88
4.104.26

285/70R17 is 1.24" taller than 285/60R18, a +3.95% change in diameter. That is more than the 3% many tire shops use as a limit, so plan on recalibrating the speedometer and checking ABS and stability control.

Ground clearance changes by 0.62" (half the diameter change), and the tire needs 0.62" more room above it.

Both tires are the same width, 11.22".

285/70R17 needs a 17" wheel instead of 18", and its sidewall is 1.12" taller.

Details: 285/60R18 in inches · 285/70R17 in inches · change sizes in the calculator

FAQ

What is the difference between 285/60R18 and 285/70R17?

285/70R17 is 1.24" taller (+3.95%) and 0.00" wider than 285/60R18.

Will 285/70R17 change my speedometer?

Yes, by +3.95%. When the speedometer shows 60 mph you would be going 62.4 mph.

Can I replace 285/60R18 with 285/70R17?

It is a +4.0% diameter change, larger than the common 3% guideline, so check clearance and plan to recalibrate.