275/70R18 vs 285/75R18

285/75R18 is 1.7" taller than 275/70R18 (5.0%)

Diameter difference+5.05%diameter 33.16" → 34.83"
275/70R18285/75R18
275/70R18285/75R18Difference
Overall diameter33.16"34.83"+1.67"
Section width10.83"11.22"+0.39"
Sidewall height7.58"8.42"+0.84"
Circumference104.2"109.4"+5.3"
Revolutions per mile608579−29
Wheel diameter18"18"±0"

Speedometer

ShowsActualDiff
30 mph31.5 mph+1.5
45 mph47.3 mph+2.3
60 mph63.0 mph+3.0
70 mph73.5 mph+3.5
80 mph84.0 mph+4.0

Gear ratio to match

CurrentEquivalent
3.423.59
3.553.73
3.733.92
4.104.31

285/75R18 is 1.67" taller than 275/70R18, a +5.05% 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 0.84" (half the diameter change), and the tire needs 0.84" more room above it.

285/75R18 is 0.39" wider. On the same wheel offset about half of that, 0.20", moves toward the suspension and half toward the fender.

Both fit a 18" wheel; the sidewall is 0.84" taller on 285/75R18.

Details: 275/70R18 in inches · 285/75R18 in inches · change sizes in the calculator

FAQ

What is the difference between 275/70R18 and 285/75R18?

285/75R18 is 1.67" taller (+5.05%) and 0.39" wider than 275/70R18.

Will 285/75R18 change my speedometer?

Yes, by +5.05%. When the speedometer shows 60 mph you would be going 63.0 mph.

Can I replace 275/70R18 with 285/75R18?

It is a +5.0% diameter change, larger than the common 3% guideline, so check clearance and plan to recalibrate.