275/70R17 is 0.1" taller than 275/65R18 (0.3%)
| 275/70R17 | 275/65R18 | Difference | |
|---|---|---|---|
| Overall diameter | 32.16" | 32.07" | −0.08" |
| Section width | 10.83" | 10.83" | ±0.00" |
| Sidewall height | 7.58" | 7.04" | −0.54" |
| Circumference | 101.0" | 100.8" | −0.3" |
| Revolutions per mile | 627 | 629 | +2 |
| Wheel diameter | 17" | 18" | +1" |
| Shows | Actual | Diff |
|---|---|---|
| 30 mph | 29.9 mph | −0.1 |
| 45 mph | 44.9 mph | −0.1 |
| 60 mph | 59.8 mph | −0.2 |
| 70 mph | 69.8 mph | −0.2 |
| 80 mph | 79.8 mph | −0.2 |
| Current | Equivalent |
|---|---|
| 3.42 | 3.41 |
| 3.55 | 3.54 |
| 3.73 | 3.72 |
| 4.10 | 4.09 |
275/65R18 is 0.08" shorter than 275/70R17, a −0.26% change in diameter, inside the 3% range most shops treat as a safe swap.
Ground clearance changes by 0.04" (half the diameter change), and the tire needs 0.04" less room above it.
Both tires are the same width, 10.83".
275/65R18 needs a 18" wheel instead of 17", and its sidewall is 0.54" shorter.
Details: 275/70R17 in inches · 275/65R18 in inches · change sizes in the calculator
275/65R18 is 0.08" shorter (−0.26%) and 0.00" wider than 275/70R17.
Yes, by −0.26%. When the speedometer shows 60 mph you would be going 59.8 mph.
Often yes: the diameter change of −0.3% is within the common 3% guideline. Check the load index, speed rating and clearance.