265/75R18 vs 275/70R18

265/75R18 is 0.5" taller than 275/70R18 (1.5%)

Diameter difference−1.46%diameter 33.65" → 33.16"
265/75R18275/70R18
265/75R18275/70R18Difference
Overall diameter33.65"33.16"−0.49"
Section width10.43"10.83"+0.39"
Sidewall height7.82"7.58"−0.25"
Circumference105.7"104.2"−1.5"
Revolutions per mile599608+9
Wheel diameter18"18"±0"

Speedometer

ShowsActualDiff
30 mph29.6 mph−0.4
45 mph44.3 mph−0.7
60 mph59.1 mph−0.9
70 mph69.0 mph−1.0
80 mph78.8 mph−1.2

Gear ratio to match

CurrentEquivalent
3.423.37
3.553.50
3.733.68
4.104.04

275/70R18 is 0.49" shorter than 265/75R18, a −1.46% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.25" (half the diameter change), and the tire needs 0.25" less room above it.

275/70R18 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 0.25" shorter on 275/70R18.

Details: 265/75R18 in inches · 275/70R18 in inches · change sizes in the calculator

FAQ

What is the difference between 265/75R18 and 275/70R18?

275/70R18 is 0.49" shorter (−1.46%) and 0.39" wider than 265/75R18.

Will 275/70R18 change my speedometer?

Yes, by −1.46%. When the speedometer shows 60 mph you would be going 59.1 mph.

Can I replace 265/75R18 with 275/70R18?

Often yes: the diameter change of −1.5% is within the common 3% guideline. Check the load index, speed rating and clearance.