285/65R18 vs 285/70R18

285/70R18 is 1.1" taller than 285/65R18 (3.4%)

Diameter difference+3.44%diameter 32.59" → 33.71"
285/65R18285/70R18
285/65R18285/70R18Difference
Overall diameter32.59"33.71"+1.12"
Section width11.22"11.22"±0.00"
Sidewall height7.29"7.85"+0.56"
Circumference102.4"105.9"+3.5"
Revolutions per mile619598−21
Wheel diameter18"18"±0"

Speedometer

ShowsActualDiff
30 mph31.0 mph+1.0
45 mph46.5 mph+1.5
60 mph62.1 mph+2.1
70 mph72.4 mph+2.4
80 mph82.8 mph+2.8

Gear ratio to match

CurrentEquivalent
3.423.54
3.553.67
3.733.86
4.104.24

285/70R18 is 1.12" taller than 285/65R18, a +3.44% 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 0.56" (half the diameter change), and the tire needs 0.56" more room above it.

Both tires are the same width, 11.22".

Both fit a 18" wheel; the sidewall is 0.56" taller on 285/70R18.

Details: 285/65R18 in inches · 285/70R18 in inches · change sizes in the calculator

FAQ

What is the difference between 285/65R18 and 285/70R18?

285/70R18 is 1.12" taller (+3.44%) and 0.00" wider than 285/65R18.

Will 285/70R18 change my speedometer?

Yes, by +3.44%. When the speedometer shows 60 mph you would be going 62.1 mph.

Can I replace 285/65R18 with 285/70R18?

It is a +3.4% diameter change, larger than the common 3% guideline, so check clearance and plan to recalibrate.