305/50R20 dimensions
| Measure | Inches | Millimetres |
|---|---|---|
| Overall height | 32.01 in | 813 mm |
| Section width | 12.01 in | 305 mm |
| Sidewall height | 6.00 in | 152.5 mm |
| Wheel diameter | 20 in | 508 mm |
| Circumference | 100.6 in | 2,554 mm |
| Revolutions per mile | 630.1 |
The math
| Step | Math | Result |
|---|---|---|
| Sidewall | 305 × 50% = 152.5 mm ÷ 25.4 | 6.00 in |
| Overall height | 20 + 2 × 6.00 | 32.01 in |
| Width | 305 mm ÷ 25.4 | 12.01 in |
| Circumference | π × 32.01 | 100.6 in |
| Revs per mile | 63,360 ÷ 100.6 | 630.1 |
With a 6.0 in sidewall this is a tall sidewall with more cushion and flex. Real tires vary by brand and model, and the loaded radius under the vehicle is a bit smaller than this unloaded figure.
One step either way on a 20 in wheel
Each row changes one thing and shows the height change against 305/50R20, plus what 60 mph on the speedometer would really be if you swapped to that size.
| Change | Size | Height | Height change | 60 mph shows as | Verdict |
|---|---|---|---|---|---|
| Wider | 315/50R20 (compare) | 32.4 in | +1.2% | 60.7 mph | Close match |
| Narrower | 295/50R20 (compare) | 31.6 in | -1.2% | 59.3 mph | Close match |
| Taller sidewall | 305/55R20 (compare) | 33.2 in | +3.8% | 62.3 mph | Check clearance |
| Shorter sidewall | 305/45R20 (compare) | 30.8 in | -3.8% | 57.7 mph | Check clearance |
| Wider, shorter sidewall | 315/45R20 (compare) | 31.2 in | -2.6% | 58.4 mph | Close match |
| Narrower, taller sidewall | 295/55R20 (compare) | 32.8 in | +2.4% | 61.4 mph | Close match |
Calculated sizes within ±3% on other wheels
Plus and minus sizes that keep the overall height within about 3% (a rule of thumb from Discount Tire and 1010tires), widths within 30 mm. Calculated, not a list of tires on sale: check that a tire exists in that size.
19 in wheels (one wheel size smaller)
| Size | Height | Height change | Width change |
|---|---|---|---|
| 275/60R19 (compare) | 32.0 in | -0.0% | -30 mm |
| 335/50R19 (compare) | 32.2 in | +0.6% | +30 mm |
| 305/55R19 (compare) | 32.2 in | +0.6% | +0 mm |
| 325/50R19 (compare) | 31.8 in | -0.7% | +20 mm |
21 in wheels (one wheel size larger)
| Size | Height | Height change | Width change |
|---|---|---|---|
| 315/45R21 (compare) | 32.2 in | +0.5% | +10 mm |
| 275/50R21 (compare) | 31.8 in | -0.6% | -30 mm |
| 305/45R21 (compare) | 31.8 in | -0.6% | +0 mm |
| 285/50R21 (compare) | 32.2 in | +0.7% | -20 mm |
22 in wheels (two wheel sizes larger)
| Size | Height | Height change | Width change |
|---|---|---|---|
| 315/40R22 (compare) | 31.9 in | -0.3% | +10 mm |
| 285/45R22 (compare) | 32.1 in | +0.3% | -20 mm |
| 325/40R22 (compare) | 32.2 in | +0.7% | +20 mm |
| 275/45R22 (compare) | 31.7 in | -0.8% | -30 mm |
Try it with your numbers
Compare 305/50R20 with another size · Convert to metric or find a 33 in size · Sizes that fit my wheel
Calculated from the size alone. Real tires vary a little by brand and model, and the loaded radius is a bit smaller. Confirm the wheel width range, clearance, load index and speed rating for your vehicle. See how to read a tire size, the load index chart and the speed rating chart.
Browse: all sizes in inches · 295/45R20 · 305/55R20.