ElpiAuto30X9.50R15 vs 235/75R15
235/75R15 is 1.12″ (29 mm) shorter than 30X9.50R15, a 3.7% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
| Measurement | 30X9.50R15 | 235/75R15 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 30.00″ | 28.88″ | −1.12″ | −3.7% |
| Section width | 9.50″ | 9.25″ | −0.25″ | −2.6% |
| Sidewall height | 7.50″ | 6.94″ | −0.56″ | −7.5% |
| Circumference | 94.25″ | 90.72″ | −3.53″ | −3.7% |
| Revs per mile | 672.3 | 698.4 | +26.1 | +3.9% |
| Revs per km | 417.7 | 434.0 | +16.2 | +3.9% |
Speedometer: with 30X9.50R15 as the original, 235/75R15 makes an indicated 60 mph really about 57.8 mph, and the axle sits ~0.56″ lower.
Reading this comparison
The overall diameter is what matters here: 30X9.50R15 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.