ElpiAuto265/70R18 vs 275/65R18
275/65R18 is 0.53″ (14 mm) shorter than 265/70R18, a 1.6% difference in overall diameter — right at the edge of the ±3% band — fine on most cars, but check clearance at full lock and full suspension compression.
| Measurement | 265/70R18 | 275/65R18 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 32.61″ | 32.07″ | −0.53″ | −1.6% |
| Section width | 10.43″ | 10.83″ | +0.39″ | +3.8% |
| Sidewall height | 7.30″ | 7.04″ | −0.27″ | −3.6% |
| Circumference | 102.44″ | 100.77″ | −1.67″ | −1.6% |
| Revs per mile | 618.5 | 628.8 | +10.2 | +1.7% |
| Revs per km | 384.3 | 390.7 | +6.4 | +1.7% |
Speedometer: with 265/70R18 as the original, 275/65R18 makes an indicated 60 mph really about 59.0 mph, and the axle sits ~0.27″ lower.
Reading this comparison
The overall diameter is what matters here: 265/70R18 is the taller tire. It sets ride height, gearing and how far the tire travels per revolution — which is what the speedometer and odometer count. Width and sidewall change fit and feel (a wider tire needs a wider wheel and more clearance; a shorter sidewall sharpens steering) but not the gearing.
Figures are geometric estimates from the size codes; real moulded tires vary by brand by 1–3%. Confirm load rating, wheel width and physical clearance on your vehicle before fitting. To compare any other two sizes, use the tire size comparison tool; to decode one size and see what else fits its wheel, the tire size calculator.