ElpiAuto275/65R18 vs 275/70R18
275/70R18 is 1.08″ (28 mm) taller than 275/65R18, a 3.4% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 275/65R18 | 275/70R18 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 32.07″ | 33.16″ | +1.08″ | +3.4% |
| Section width | 10.83″ | 10.83″ | — | |
| Sidewall height | 7.04″ | 7.58″ | +0.54″ | +7.7% |
| Circumference | 100.77″ | 104.17″ | +3.40″ | +3.4% |
| Revs per mile | 628.8 | 608.3 | −20.5 | −3.3% |
| Revs per km | 390.7 | 378.0 | −12.8 | −3.3% |
Speedometer: with 275/65R18 as the original, 275/70R18 makes an indicated 60 mph really about 62.0 mph, and the axle sits ~0.54″ higher.
Reading this comparison
The overall diameter is what matters here: 275/70R18 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.