275/70R18 vs 285/65R18

275/70R18 is 0.6" taller than 285/65R18 (1.7%)

Diameter difference−1.72%diameter 33.16" → 32.59"
275/70R18285/65R18
275/70R18285/65R18Difference
Overall diameter33.16"32.59"−0.57"
Section width10.83"11.22"+0.39"
Sidewall height7.58"7.29"−0.29"
Circumference104.2"102.4"−1.8"
Revolutions per mile608619+11
Wheel diameter18"18"±0"

Speedometer

ShowsActualDiff
30 mph29.5 mph−0.5
45 mph44.2 mph−0.8
60 mph59.0 mph−1.0
70 mph68.8 mph−1.2
80 mph78.6 mph−1.4

Gear ratio to match

CurrentEquivalent
3.423.36
3.553.49
3.733.67
4.104.03

285/65R18 is 0.57" shorter than 275/70R18, a −1.72% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.29" (half the diameter change), and the tire needs 0.29" less room above it.

285/65R18 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 0.29" shorter on 285/65R18.

Details: 275/70R18 in inches · 285/65R18 in inches · change sizes in the calculator

FAQ

What is the difference between 275/70R18 and 285/65R18?

285/65R18 is 0.57" shorter (−1.72%) and 0.39" wider than 275/70R18.

Will 285/65R18 change my speedometer?

Yes, by −1.72%. When the speedometer shows 60 mph you would be going 59.0 mph.

Can I replace 275/70R18 with 285/65R18?

Often yes: the diameter change of −1.7% is within the common 3% guideline. Check the load index, speed rating and clearance.