ElpiAuto275/70R18 vs 325/60R18
325/60R18 is 0.20″ (5 mm) taller than 275/70R18, a 0.6% difference in overall diameter — comfortably inside the ±3% band most fitment guides use, so it swaps straight across for gearing and the speedometer.
| Measurement | 275/70R18 | 325/60R18 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 33.16″ | 33.35″ | +0.20″ | +0.6% |
| Section width | 10.83″ | 12.80″ | +1.97″ | +18.2% |
| Sidewall height | 7.58″ | 7.68″ | +0.10″ | +1.3% |
| Circumference | 104.17″ | 104.79″ | +0.62″ | +0.6% |
| Revs per mile | 608.3 | 604.7 | −3.6 | −0.6% |
| Revs per km | 378.0 | 375.7 | −2.2 | −0.6% |
Speedometer: with 275/70R18 as the original, 325/60R18 makes an indicated 60 mph really about 60.4 mph, and the axle sits ~0.10″ higher.
Reading this comparison
The overall diameter is what matters here: 325/60R18 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.