ElpiAuto30X9.50R15 vs 35X12.50R15
35X12.50R15 is 5.00″ (127 mm) taller than 30X9.50R15, a 16.7% difference in overall diameter — outside the ±3% band, so expect the speedometer to drift and check for rubbing before fitting.
The section widths are very different — these are not a like-for-like swap. Confirm wheel width and arch clearance separately.
| Measurement | 30X9.50R15 | 35X12.50R15 | Difference | % |
|---|---|---|---|---|
| Overall diameter | 30.00″ | 35.00″ | +5.00″ | +16.7% |
| Section width | 9.50″ | 12.50″ | +3.00″ | +31.6% |
| Sidewall height | 7.50″ | 10.00″ | +2.50″ | +33.3% |
| Circumference | 94.25″ | 109.96″ | +15.71″ | +16.7% |
| Revs per mile | 672.3 | 576.2 | −96.0 | −14.3% |
| Revs per km | 417.7 | 358.1 | −59.7 | −14.3% |
Speedometer: with 30X9.50R15 as the original, 35X12.50R15 makes an indicated 60 mph really about 70.0 mph, and the axle sits ~2.50″ higher.
Reading this comparison
The overall diameter is what matters here: 35X12.50R15 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.