ElpiAuto305/70R16 vs 315/75R16
315/75R16 is 1.79″ (46 mm) taller than 305/70R16, a 5.5% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 305/70R16 | 315/75R16 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 32.81″ | 34.60″ | +1.79″ | +5.5% |
| Section width | 12.01″ | 12.40″ | +0.39″ | +3.3% |
| Sidewall height | 8.41″ | 9.30″ | +0.90″ | +10.7% |
| Circumference | 103.08″ | 108.71″ | +5.63″ | +5.5% |
| Revs per mile | 614.7 | 582.9 | −31.8 | −5.2% |
| Revs per km | 381.9 | 362.2 | −19.8 | −5.2% |
Speedometer: with 305/70R16 as the original, 315/75R16 makes an indicated 60 mph really about 63.3 mph, and the axle sits ~0.90″ higher.
Reading this comparison
The overall diameter is what matters here: 315/75R16 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.