285/60R20 — what a three-quarter-ton leaves the factory on
A factory heavy-duty size sitting where the aftermarket usually has to go looking.
Metric notation · Light truck (LT-metric)
- Overall diameter
- 33.46 in
- 850 mm
- Section width
- 11.22 in
- 285 mm
- Sidewall height
- 6.73 in
- 171 mm
- Aspect ratio
- 60%
- sidewall as a share of width
- Wheel diameter
- 20 in
- the hole in the middle
- Circumference
- 105.1 in
- 2670 mm
- Revolutions per mile
- 602.7
- geometric, not measured
- Revolutions per km
- 374.5
- geometric, not measured
- Typical load index
- 108–129
- 2205–4079 lb per tire
LT-metric tires use a stiffer casing at a much higher reference inflation — Load Range C, D or E, meaning 50, 65 or 80 psi. The index band reflects the pressure the casing is rated to hold, not a larger tire.
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
- 33x12.50R2033.00 in tall-0.46 in
- 35x12.50R2035.00 in tall+1.54 in
- 37x12.50R2037.00 in tall+3.54 in
Compare any two sizes, including ones this site has no page for, in the comparison tool.
Platforms recorded with this size
Two heavy-duty pickups ship 285/60R20 — the fourth-generation F-250 Super Duty and the fourth-generation Ram 2500 — and a half-ton, the third-generation Silverado 1500, lists it as an upgrade instead. That split is the whole character of the size: standard equipment at one end of the market and a deliberate step at the other.
Half an inch from the flotation 33
33x12.50R20 stands 33.00 in. This size stands 33.46 in, which makes it 0.46 in taller and 1.28 in narrower. 305/55R20 is closer still, 0.26 in below at 33.21 in on 12.01 in of section.
A truck already delivered on this tire is therefore within one and a half per cent of the tire most of its owners would consider fitting. What a 33 offers over it is 1.28 in of section width, and what it costs is a speedometer reading 1.39% slow — an indicated 70 mph becoming 69.0.
Where it sits on a crowded wheel
| Size | Diameter | Against 285/60R20 |
|---|---|---|
| 275/55R20 | 31.91 in | −1.56 in (4.65%) |
| 265/60R20 | 32.52 in | −0.94 in |
| 275/60R20 | 32.99 in | −0.47 in |
| 285/60R20 | 33.46 in | — |
| 275/65R20 | 34.07 in | +0.61 in |
| 285/65R20 | 34.59 in | +1.12 in (3.35%) |
| 35x12.50R20 | 35.00 in | +1.54 in (4.59%) |
Twenty-one sizes share the 20-inch wheel in this catalogue, more than any wheel except the 17 and the 18, and the truck half of that range is packed tightly enough that every row above is within five per cent of every other.
The same aspect ratio, two inches of wheel down
285/60R18 carries the identical section width and the identical 60 aspect ratio, and it stands 31.46 in — exactly 2.00 in shorter, because the only thing that changed is the wheel. Its sidewall is the same 6.73 in as this size's.
That pair is the cleanest illustration on this wheel of what a wheel-diameter change does on its own: the casing is unaltered in every dimension, and the tire's standing height moves by precisely the difference in rim. Everything else people attribute to "going up a wheel size" comes from the aspect ratio being changed at the same time. The plus sizing reference separates the two effects.
Related
- 33x12.50R2033.00 in tall
- 35x12.50R2035.00 in tall
- 37x12.50R2037.00 in tall
Class: Light truck (LT-metric). Every figure above is computed from the size code, not stored — see how these numbers are calculated.