255/40R17 dimensions
| Measure | Inches | Millimetres |
|---|---|---|
| Overall height | 25.03 in | 636 mm |
| Section width | 10.04 in | 255 mm |
| Sidewall height | 4.02 in | 102.0 mm |
| Wheel diameter | 17 in | 432 mm |
| Circumference | 78.6 in | 1,997 mm |
| Revolutions per mile | 805.7 |
The math
| Step | Math | Result |
|---|---|---|
| Sidewall | 255 × 40% = 102.0 mm ÷ 25.4 | 4.02 in |
| Overall height | 17 + 2 × 4.02 | 25.03 in |
| Width | 255 mm ÷ 25.4 | 10.04 in |
| Circumference | π × 25.03 | 78.6 in |
| Revs per mile | 63,360 ÷ 78.6 | 805.7 |
With a 4.0 in sidewall this is a medium sidewall: a balance of cushion and response. 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 17 in wheel
Each row changes one thing and shows the height change against 255/40R17, 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 | 265/40R17 (compare) | 25.3 in | +1.3% | 60.8 mph | Close match |
| Narrower | 245/40R17 (compare) | 24.7 in | -1.3% | 59.2 mph | Close match |
| Taller sidewall | 255/45R17 (compare) | 26.0 in | +4.0% | 62.4 mph | Check clearance |
| Shorter sidewall | 255/35R17 (compare) | 24.0 in | -4.0% | 57.6 mph | Check clearance |
| Wider, shorter sidewall | 265/35R17 (compare) | 24.3 in | -2.9% | 58.3 mph | Close match |
| Narrower, taller sidewall | 245/45R17 (compare) | 25.7 in | +2.6% | 61.6 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.
16 in wheels (one wheel size smaller)
| Size | Height | Height change | Width change |
|---|---|---|---|
| 255/45R16 (compare) | 25.0 in | +0.0% | +0 mm |
| 285/40R16 (compare) | 25.0 in | -0.2% | +30 mm |
| 225/50R16 (compare) | 24.9 in | -0.7% | -30 mm |
| 235/50R16 (compare) | 25.3 in | +0.9% | -20 mm |
18 in wheels (one wheel size larger)
| Size | Height | Height change | Width change |
|---|---|---|---|
| 255/35R18 (compare) | 25.0 in | -0.0% | +0 mm |
| 225/40R18 (compare) | 25.1 in | +0.2% | -30 mm |
| 265/35R18 (compare) | 25.3 in | +1.1% | +10 mm |
| 245/35R18 (compare) | 24.8 in | -1.1% | -10 mm |
19 in wheels (two wheel sizes larger)
| Size | Height | Height change | Width change |
|---|---|---|---|
| 255/30R19 (compare) | 25.0 in | -0.0% | +0 mm |
| 225/35R19 (compare) | 25.2 in | +0.7% | -30 mm |
| 265/30R19 (compare) | 25.3 in | +0.9% | +10 mm |
| 245/30R19 (compare) | 24.8 in | -1.0% | -10 mm |
Try it with your numbers
Compare 255/40R17 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 · 245/75R17 · 255/50R17.