295/70R17 vs 275/70R18

295/70R17 is 0.1" taller than 275/70R18 (0.3%)

Diameter difference−0.31%diameter 33.26" → 33.16"
295/70R17275/70R18
295/70R17275/70R18Difference
Overall diameter33.26"33.16"−0.10"
Section width11.61"10.83"−0.79"
Sidewall height8.13"7.58"−0.55"
Circumference104.5"104.2"−0.3"
Revolutions per mile606608+2
Wheel diameter17"18"+1"

Speedometer

ShowsActualDiff
30 mph29.9 mph−0.1
45 mph44.9 mph−0.1
60 mph59.8 mph−0.2
70 mph69.8 mph−0.2
80 mph79.8 mph−0.2

Gear ratio to match

CurrentEquivalent
3.423.41
3.553.54
3.733.72
4.104.09

275/70R18 is 0.10" shorter than 295/70R17, a −0.31% change in diameter, inside the 3% range most shops treat as a safe swap.

Ground clearance changes by 0.05" (half the diameter change), and the tire needs 0.05" less room above it.

295/70R17 is 0.79" wider. On the same wheel offset about half of that, 0.39", moves toward the suspension and half toward the fender.

275/70R18 needs a 18" wheel instead of 17", and its sidewall is 0.55" shorter.

Details: 295/70R17 in inches · 275/70R18 in inches · change sizes in the calculator

FAQ

What is the difference between 295/70R17 and 275/70R18?

275/70R18 is 0.10" shorter (−0.31%) and 0.79" narrower than 295/70R17.

Will 275/70R18 change my speedometer?

Yes, by −0.31%. When the speedometer shows 60 mph you would be going 59.8 mph.

Can I replace 295/70R17 with 275/70R18?

Often yes: the diameter change of −0.3% is within the common 3% guideline. Check the load index, speed rating and clearance.