37x13.50R17 — same casing depth, lower aspect ratio
Proof that an aspect ratio describes a proportion and cannot be read as a depth.
Flotation (imperial) notation · Flotation (imperial)
- Overall diameter
- 37.00 in
- 940 mm
- Section width
- 13.50 in
- 343 mm
- Sidewall height
- 10.00 in
- 254 mm
- Aspect ratio
- 74.1%
- sidewall as a share of width
- Wheel diameter
- 17 in
- the hole in the middle
- Circumference
- 116.2 in
- 2952 mm
- Revolutions per mile
- 545.1
- geometric, not measured
- Revolutions per km
- 338.7
- geometric, not measured
- Typical load index
- 108–128
- 2205–3968 lb per tire
Flotation sizes are almost always LT construction, so they share the light-truck band. Speed symbols run low because the aggressive tread patterns these sizes are sold in are rated against heat build-up, not against sustained high speed.
The load-index range shown is the band this CLASS of size is typically produced in — not a list of what is in stock for this exact size today. Load index and speed symbol are printed on the sidewall of the specific tire you are holding, and the required minimum is on the placard of the specific vehicle you are fitting. Read both.
Nearest real sizes in metric notation, same wheel
- 315/70R1734.36 in tall-2.64 in
- 305/70R1733.81 in tall-3.19 in
- 295/70R1733.26 in tall-3.74 in
Compare any two sizes, including ones this site has no page for, in the comparison tool.
No vehicle in this catalogue lists 37x13.50R17. It is the wide member of the 37-inch pair on a 17-inch wheel, and it shares that wheel with the largest tire on the site.
Identical casings, different ratios
Both 37s on this wheel put 10.00 in of rubber between the rim and the road, because both are 37 in tall on a 17-inch wheel and the subtraction does not care about width.
Divide that 10.00 in by the section width and the two diverge. Against 12.50 in the ratio is 80. Against this size's 13.50 in it is 74. Six points of difference between two tires with the same casing depth, arising entirely from what the depth is being measured against.
Neither number is printed on either tire, which is fortunate, because a buyer told that one of them was a 74-series and the other an 80-series would reasonably conclude that the second had more sidewall. It does not. It has a narrower tread.
The 17-inch wheel's top end
| Size | Diameter | Section width | Sidewall |
|---|---|---|---|
| 315/70R17 | 34.36 in | 12.40 in | 8.68 in |
| 35x11.50R17 | 35.00 in | 11.50 in | 9.00 in |
| 35x12.50R17 | 35.00 in | 12.50 in | 9.00 in |
| 37x12.50R17 | 37.00 in | 12.50 in | 10.00 in |
| 37x13.50R17 | 37.00 in | 13.50 in | 10.00 in |
| 40x13.50R17 | 40.00 in | 13.50 in | 11.50 in |
This size and the one below it are separated by 1.00 in of tread and nothing else. This size and the one above it are separated by 3.00 in of height and nothing else. Between them those two pairs account for the entire top of the 17-inch range.
Down to the metric alternatives
The nearest metric code is 315/70R17 at 34.36 in — 2.64 in shorter, 7.13% by this size's measurement, and 1.10 in narrower. Below that the drop steepens: 305/70R17 is 3.19 in down and 295/70R17 is 3.74 in down.
Metric notation on a 17-inch wheel simply does not reach this height, which is why every size at or above 35 in on this wheel is written the imperial way. The metric versus imperial reference covers where the two systems stop overlapping.
Related
Class: Flotation (imperial). Every figure above is computed from the size code, not stored — see how these numbers are calculated.