ElpiAuto275/70R18 vs 285/75R18
285/75R18 is 1.67″ (42 mm) taller than 275/70R18, a 5.0% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 275/70R18 | 285/75R18 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 33.16″ | 34.83″ | +1.67″ | +5.0% |
| Section width | 10.83″ | 11.22″ | +0.39″ | +3.6% |
| Sidewall height | 7.58″ | 8.42″ | +0.84″ | +11.0% |
| Circumference | 104.17″ | 109.42″ | +5.26″ | +5.0% |
| Revs per mile | 608.3 | 579.0 | −29.2 | −4.8% |
| Revs per km | 378.0 | 359.8 | −18.2 | −4.8% |
Speedometer: with 275/70R18 as the original, 285/75R18 makes an indicated 60 mph really about 63.0 mph, and the axle sits ~0.84″ higher.
Reading this comparison
The overall diameter is what matters here: 285/75R18 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.