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Tire sizes

225/75R16 — where the light-truck range begins on a 16

A van and light-truck size that sits exactly on the boundary between two very different parts of the catalogue.

Metric notation · Light truck (LT-metric)

Overall diameter
29.29 in
744 mm
Section width
8.86 in
225 mm
Sidewall height
6.64 in
169 mm
Aspect ratio
75%
sidewall as a share of width
Wheel diameter
16 in
the hole in the middle
Circumference
92.0 in
2337 mm
Revolutions per mile
688.6
geometric, not measured
Revolutions per km
427.9
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

  • 31x10.50R1631.00 in tall+1.71 in
  • 33x12.50R1633.00 in tall+3.71 in
  • 35x12.50R1635.00 in tall+5.71 in

Compare any two sizes, including ones this site has no page for, in the comparison tool.

Platforms recorded with this size

Full-size vans, older three-quarter-ton pickups in base specification, and a range of commercial chassis. It is the narrowest and shortest of the 16-inch light-truck sizes here, which puts it at the exact point where the light-truck ladder overlaps the crossover one.

The boundary, in revolutions per mile

Size Class Diameter Revolutions per mile
235/65R17 crossover 29.03 in 694.8
225/75R16 light truck 29.29 in 688.6
245/65R17 crossover 29.54 in 682.8
235/60R18 crossover 29.10 in 693.0

Four sizes inside a single inch of diameter, three of them designed for unibody crossovers and one for a commercial van. Nothing in the geometry distinguishes them — the difference is entirely in the casing construction and the load rating, neither of which appears in the size code.

Revolutions per mile is the figure that connects tire size to gearing: it is what the axle ratio is multiplied against to give engine speed at a road speed. Across the four sizes above the spread is 12 revolutions per mile, which is under 2%.

Against the flotation ladder

30x9.50R15 measures 30.00 in — 0.71 in and 2.43% above this size, on a wheel an inch smaller and with a full 7.50 in of sidewall. That pairing is a good illustration of how little wheel diameter constrains tire height: the smaller wheel carries the taller tire comfortably.

The load index is the point of this size

A crossover tire and a van tire standing the same height are not interchangeable in any sense that matters to a loaded vehicle. Sizes in this part of the catalogue are stocked in LT and commercial constructions with load indexes well above the passenger equivalents, and the reference inflation they are rated at is much higher.

On a commercial vehicle the rating is not a single figure either. What a casing can carry depends on what it is inflated to, and the manufacturer publishes that as a table rather than a number — which is why the pressure on a van's placard is often far above what the same size would run on a car. The tire pressure and load tables reference sets out how the two are tied together, and the load range and ply rating reference covers the older markings still stamped alongside.

Related

Class: Light truck (LT-metric). Every figure above is computed from the size code, not stored — see how these numbers are calculated.