285/75R16 — the 16-inch size no truck comes with

Four upgrade lists and no factory list

The third and second generation Toyota Tacoma, the fifth-generation Toyota 4Runner and the Nissan Frontier D40 all name 285/75R16 among their common upgrades. No vehicle in the catalogue leaves the factory on it. The 4Runner's record writes it LT285/75R16; the other three write it plain.

What it is doing on a 16-inch wheel

Sort every catalogued size that fits a 16-inch wheel by height and there is a conspicuous hole near the top. Below it, 235/85R16 stands 31.73 in. Above it, 33x12.50R16 stands 33.00 in. Between those two figures there is exactly one size, and this is it.

That is the whole reason the tire exists in this width. A 16-inch wheel cannot get to 33 inches on a metric code without an aspect ratio in the 80s, and the only 80-series entry available is 1.97 in narrower. 285/75R16 reaches 32.83 in on a wide casing instead.

Seventeen hundredths of an inch from a real 33

33x12.50R16 measures 33.00 in. The gap is 0.17 in — 0.52%. Fitting one in place of the other turns an indicated 70 mph into an actual 70.4 mph, which no driver will ever detect.

Where they part company is width: 12.50 in against 11.22 in, a difference of 1.28 in. That is the practical choice these four platforms present, and the arithmetic is almost silent on it.

The same height on a 22-inch wheel

Set 285/75R16 next to 275/50R22 and both compute to 32.83 in. One is an off-road upgrade for a twenty-year-old mid-size pickup; the other is a factory fitment on a full-size SUV with wheels six inches larger in diameter.

The sidewalls tell the story the diameters conceal: 8.42 in here, 5.41 in there. Same rolling height, same speedometer calibration, same revolutions per mile to within a rounding error, and almost nothing else in common.

It is a useful pairing to keep in mind whenever a diameter is quoted on its own. Overall diameter is the only figure that drives the arithmetic, and it is also the figure that tells you least about what a tire will feel like or what it will fit inside. Two tires can agree on it to the hundredth of an inch and be built for entirely different vehicles.

Coming up to it

Coming from	Diameter	Step	Speed at an indicated 70 mph
245/75R16	30.47 in	+2.36 in (7.75%)	75.4 mph
265/70R16	30.61 in	+2.22 in (7.27%)	75.1 mph
31x10.50R16	31.00 in	+1.83 in (5.91%)	74.1 mph
265/75R16	31.65 in	+1.18 in (3.73%)	72.6 mph
235/85R16	31.73 in	+1.10 in (3.47%)	72.4 mph

A detail worth noticing in that table: the percentage for a given swap depends on which tire you start from. Going from 265/70R16 up to this size is 7.27%. Coming back down is 6.78% — the same 2.22 in, divided by a bigger number. Percentages of tire diameter are not symmetrical, and the direction matters when quoting one.

Why the step is never small

Look at the 16-inch sizes those four trucks actually leave the factory on and the reason for the table above becomes obvious. The Tacomas and the 4Runner ship 245/75R16 or 265/70R16, at 30.47 in and 30.61 in. The Frontier D40 adds 265/75R16 at 31.65 in.

So the smallest jump to this size available on any of them is 1.18 in, from the Frontier's tallest factory tire, and the largest is 2.36 in. There is no gentle version of this upgrade, because the sizes that would provide one — something around 32 in on a 16-inch wheel — are simply not made in volume. The wheel diameter that dominated mid-size trucks in 2005 stopped attracting new size development long before the aftermarket lost interest in it.

The one larger 16-inch option

35x12.50R16 at 35.00 in is the only larger option catalogued on this wheel: +2.17 in and 6.61%, or an actual 74.6 mph at an indicated 70.

285 millimetres is the most travelled width in the catalogue

Ten catalogued codes carry a 285 mm section, and they are spread across five wheel diameters — 16, 17, 18, 20 and 22 inches. No other width reaches that far.

The heights they produce run from 27.85 in, on the low-profile 285/35R20, to 34.83 in on 285/75R18. That is a seven-inch range built out of one nominal casing width, using nothing but aspect ratio and wheel diameter.

This size sits close to the middle of that spread and at the bottom of the wheel range. Its sidewall, 8.42 in, is the joint deepest of the ten — matched only by 285/75R18, which uses the same 75 aspect on two more inches of wheel and therefore stands 2.00 in taller.

Which is the compact statement of what a 16-inch wheel now buys: not a small tire, and not a cheap one, but the deepest casing any 285 mm code in this catalogue is built with.