235/60R18 — 1990s truck tread on three inches more wheel
A mid-size crossover fitment whose closest relative in the catalogue is a light-truck size from three wheel generations earlier.
Metric notation · Crossover and SUV
- Overall diameter
- 29.10 in
- 739 mm
- Section width
- 9.25 in
- 235 mm
- Sidewall height
- 5.55 in
- 141 mm
- Aspect ratio
- 60%
- sidewall as a share of width
- Wheel diameter
- 18 in
- the hole in the middle
- Circumference
- 91.4 in
- 2322 mm
- Revolutions per mile
- 693.0
- geometric, not measured
- Revolutions per km
- 430.6
- geometric, not measured
- Typical load index
- 98–116
- 1653–2756 lb per tire
Crossovers are heavier than the cars they share size families with, so the same nominal size is produced at a higher index for SUV fitment than for passenger fitment. Two tires wearing the same size code can carry materially different loads.
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 imperial notation, same wheel
- 33x12.50R1833.00 in tall+3.90 in
- 35x12.50R1835.00 in tall+5.90 in
- 37x12.50R1837.00 in tall+7.90 in
Compare any two sizes, including ones this site has no page for, in the comparison tool.
Platforms recorded with this size
Mid-size and three-row crossovers use this size in their mid trims — Highlander, Pilot, Santa Fe, Traverse and the like.
Thirty years apart, the same tread width, the same height
235/75R15 measures 28.88 in. This size measures 29.10 in. The gap is 0.22 in, or 0.77%. Both are 9.25 in wide at the section, because both carry a 235 mm casing.
Everything else moved. The wheel went from 15 in to 18 in — three full inches — and the sidewall came down from 6.94 in to 5.55 in to absorb it. The older size went on compact pickups and body-on-frame SUVs; this one goes on unibody crossovers that do the same job for most owners.
The rolling diameter did not move because it could not: gearing, arch clearance and drivetrain calibration all constrain it, and none of them cared what the wheel was doing.
The 18-inch crossover band
| Size | Diameter | Section | Sidewall |
|---|---|---|---|
| 235/60R18 | 29.10 in | 9.25 in | 5.55 in |
| 245/60R18 | 29.57 in | 9.65 in | 5.79 in |
| 235/65R18 | 30.03 in | 9.25 in | 6.01 in |
| 255/60R18 | 30.05 in | 10.04 in | 6.02 in |
The 235/65R18 and 255/60R18 entries land 0.02 in apart from completely different codes — one adds five points of aspect ratio, the other adds 20 mm of width, and they arrive at the same place.
Its 17-inch counterpart
235/65R17 measures 29.03 in, which is 0.26% from this size on the same 9.25 in section. An inch less wheel, five points more aspect ratio, and no meaningful change in standing height. Both sizes appear on the same vehicles in adjacent trims for that reason.
Ratings
Wheel diameter is the only element of a size code that is already a length rather than an input to one, which is why the 15-to-18 change above is exactly three inches while every other difference between those two sizes had to be calculated.
Three-row crossovers are also where the gearing consequences of a size change stop being academic. At 693.0 revolutions per mile this size is turning the final drive slower than the 15-inch size it descends from, and in a vehicle with a wide-ratio automatic that shows up as which gear it holds on a gradient rather than as a number on a dial. The transmission gear ratios reference explains where the tire sits in that chain, and the comparison tool handles any pairing.
Related
- 33x12.50R1833.00 in tall
- 35x12.50R1835.00 in tall
- 37x12.50R1837.00 in tall
Class: Crossover and SUV. Every figure above is computed from the size code, not stored — see how these numbers are calculated.