37x13.50R18 vs 37x12.50R20
37x12.50R20 is 0.00 in (0.0 mm) taller than 37x13.50R18, a 0.00% diameter difference. With the speedometer set for 37x13.50R18, an indicated 60 mph is 60.0 mph on 37x12.50R20.
Is this a safe swap?
Diameter difference 0.00%: under 1%
By overall diameter alone, 37x12.50R20 is a near match for 37x13.50R18; the speedometer changes by less than 1%. This check uses diameter only. It does not assess load index, speed rating, wheel width or clearance.
| Measurement | 37x13.50R18 | 37x12.50R20 | Difference | % diff |
|---|---|---|---|---|
| Overall diameter | 37.00 in (939.8 mm) | 37.00 in (939.8 mm) | 0.00 in (0.0 mm) | 0.00% |
| Sidewall height | 9.50 in (241.3 mm) | 8.50 in (215.9 mm) | −1.00 in (−25.4 mm) | −10.53% |
| Section width | 13.50 in (342.9 mm) | 12.50 in (317.5 mm) | −1.00 in (−25.4 mm) | −7.41% |
| Circumference | 116.24 in (2,952.5 mm) | 116.24 in (2,952.5 mm) | 0.00 in (0.0 mm) | 0.00% |
| Revolutions per mile | 545 | 545 | 0 | 0.00% |
| Indicated | Actual on 37x13.50R18 | Actual on 37x12.50R20 | Difference |
|---|---|---|---|
| 30 mph | 30.0 mph | 30.0 mph | 0.0 mph |
| 60 mph | 60.0 mph | 60.0 mph | 0.0 mph |
| 75 mph | 75.0 mph | 75.0 mph | 0.0 mph |
Ride-height change: 37x12.50R20 does not change the vehicle at the axle (half the 0.0 mm diameter difference).
37x12.50R20 is the same height as 37x13.50R18 and 25 mm narrower, a 0.00% difference in overall diameter.
With the speedometer calibrated for 37x13.50R18, an indicated 60 mph is actually 60.0 mph on 37x12.50R20, and revolutions per mile change from 545 to 545.
37x12.50R20 mounts on a 20-inch wheel, a plus-2 fitment from the 18-inch wheel of 37x13.50R18.
Size pages
- 37x13.50R18 dimensions
- 37x12.50R20 dimensions
- All 18-inch sizes
- All 20-inch sizes
- Open in the calculator
Other comparisons with 37x13.50R18
- 315/75R17 vs 37x13.50R18
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- 37x13.50R17 vs 37x13.50R18
- 315/70R18 vs 37x13.50R18
- 37x12.50R18 vs 37x13.50R18
- 37x13.50R18 vs 325/60R20
- 37x13.50R18 vs 37x13.50R20
- 37x13.50R18 vs 38x13.50R20
Other comparisons with 37x12.50R20
- 315/70R18 vs 37x12.50R20
- 37x12.50R18 vs 37x12.50R20
- 325/60R20 vs 37x12.50R20
- 37x12.50R20 vs 37x13.50R20
- 37x12.50R20 vs 38x13.50R20
- 37x12.50R20 vs 38x15.50R20
- 37x12.50R20 vs 37x13.50R22
Source: Calculated from standard tire geometry formulas. Verified . How these numbers are calculated.