235/65R18 tire size — six codes at thirty inches
Thirty inches is where more of the catalogue converges than at any other height.
Metric notation · Crossover and SUV
- Overall diameter
- 30.03 in
- 763 mm
- Section width
- 9.25 in
- 235 mm
- Sidewall height
- 6.01 in
- 153 mm
- Aspect ratio
- 65%
- sidewall as a share of width
- Wheel diameter
- 18 in
- the hole in the middle
- Circumference
- 94.3 in
- 2396 mm
- Revolutions per mile
- 671.7
- geometric, not measured
- Revolutions per km
- 417.3
- 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+2.97 in
- 35x12.50R1835.00 in tall+4.97 in
- 37x12.50R1837.00 in tall+6.97 in
Compare any two sizes, including ones this site has no page for, in the comparison tool.
Three-row crossovers and mid-size SUVs in their upper trims: Highlander, Pilot, Telluride, Atlas and their relatives.
Six sizes, five wheel diameters, three hundredths of an inch
| Size | Wheel | Diameter | Section | Sidewall |
|---|---|---|---|---|
| 30x9.50R15 | 15 in | 30.00 in | 9.50 in | 7.50 in |
| 235/65R18 | 18 in | 30.03 in | 9.25 in | 6.01 in |
| 255/55R19 | 19 in | 30.04 in | 10.04 in | 5.52 in |
| 255/60R18 | 18 in | 30.05 in | 10.04 in | 6.02 in |
| 255/65R17 | 17 in | 30.05 in | 10.04 in | 6.53 in |
| 255/70R16 | 16 in | 30.06 in | 10.04 in | 7.03 in |
Every one of those is within 0.03 in of every other. The sidewalls run from 5.52 in to 7.50 in and the wheels from 15 to 19 inches, and the whole set rolls the same distance per revolution.
Four of them are the same 255 mm casing at four aspect ratios on four wheels — a deliberately constructed plus-size stack. One is a flotation size from a different notation entirely. This size arrives at the same place with a narrower 235 mm section.
Why thirty inches specifically
Because it is the rolling diameter the crossover and mid-size SUV class settled on, and because five points of aspect ratio at 255 mm happens to be worth almost exactly one inch — so a stack built around 255 mm lands on round-numbered diameters at every wheel size. The plus sizing reference works through how such a stack is constructed.
A dense band of 18-inch crossover packages
245/60R18 is 0.45 in shorter at 29.57 in; 265/60R18 is 0.49 in taller at 30.52 in; 255/65R18 is 1.02 in taller at 31.05 in. The 18-inch crossover range is dense around this diameter, which is why so many vehicles offer three or four wheel-and-tire packages that differ mainly in appearance.
What the door-jamb placard settles that this page cannot
Every size in the table above rolls the same distance per revolution, so none of them would change a speedometer reading. What separates them is rated capacity, and that is a property of the individual casing rather than of any dimension here — a flotation tire built for a light truck and a passenger-rated crossover tire can stand the same height and be hundreds of pounds apart.
The vehicle's placard states the minimum index it was certified with. The load index table turns an index into pounds and kilograms so the two can be compared directly.
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.