265/70R16 — 30.61 in, and exactly an inch under its 17-inch namesake

The trucks that stayed on 16s

Full-size pickups had largely abandoned the 16-inch wheel by the mid-2000s. Mid-size trucks did not. The vehicle records here list 265/70R16 as a factory size on the second-generation Toyota Tacoma from 2005, the third generation from 2016, the fifth-generation 4Runner from 2010, and the Nissan Frontier D40 from 2005 — three of those overlapping in production for the better part of a decade.

The one-inch rule, and the error it catches

Overall diameter is the wheel diameter plus twice the sidewall height. Sidewall height depends on the first two numbers in the code and on nothing else. So when two metric sizes share a section width and an aspect ratio and differ only in the wheel they are built for, the difference in overall diameter is the difference in wheel diameter — exactly, with no rounding and no residue.

265/70R16 is 30.61 in. 265/70R17 is 31.61 in. The gap is 1.00 in because the wheel is one inch bigger, and for no other reason.

That is worth stating plainly because these two codes are the most commonly confused pair in the mid-size truck world, and quoting the 17-inch figure for the 16-inch tire puts every downstream number out by a full inch: the ride-height change, the speedometer percentage, the gearing. A number that is wrong by exactly 1.00 in looks entirely plausible, which is what makes it survive.

What a 16-inch wheel still offers, and what it does not

The upside is on the page above: 7.30 in of sidewall, which is a great deal of air for a tire only just over 30 in tall. The constraint is choice. This catalogue holds 17 genuinely-sold sizes on a 16-inch wheel against 38 on a 17, and most of the 16-inch entries are either small passenger sizes or truck sizes in a narrow band between 29 and 33 in.

The 31 that is hardly a step

31x10.50R16 measures 31.00 in and 10.50 in wide. Against 265/70R16 that is +0.39 in of height and +0.07 in of width — a 1.29% change in diameter, which is less than the manufacturing variation between two brands of the same size. The two are functionally the same tire expressed in two notations, and the flotation one merely states its diameter out loud.

Where these platforms actually go

Target	Diameter	Change	Section width
265/75R16	31.65 in	+1.04 in (3.41%)	10.43 in, unchanged
235/85R16	31.73 in	+1.12 in (3.67%)	9.25 in
285/75R16	32.83 in	+2.22 in (7.27%)	11.22 in
33x12.50R16	33.00 in	+2.39 in (7.82%)	12.50 in

The bottom two rows are where the speedometer stops being a rounding argument. At 7.27%, an indicated 70 mph is an actual 75.1 mph and an indicated 100 miles is 107.3. At 7.82% it is 75.5 mph.

There is also a step down that gets asked about, because it sits so close: 245/75R16 at 30.47 in is 0.14 in shorter than this size and 0.79 in narrower. That is 0.45%, which is nothing at all on an instrument cluster, and it is why the two show up on adjacent trim levels of the same truck.

The narrow outlier in that table

235/85R16 deserves a separate note because it does not belong to the same progression as the rest. It is 1.12 in taller than 265/70R16 and simultaneously 1.18 in narrower. Every other route to a taller tire on this wheel adds width; this one removes it. That combination — tall, thin, on a 16-inch wheel — exists because the 85 aspect ratio is still produced in this size, and there is almost nothing else on any modern wheel diameter that reaches it.

Deep ratios behind a short tire

The platforms on this size are geared unusually low. The third-generation Tacoma is recorded with 3.909 and 4.30 axle options and the 4Runner with 3.727 — numbers that would look extreme under a half-ton pickup and are routine here, because a 30.61 in tire turning 659.0 times in a mile needs less mechanical advantage than a 33 does.

That is the same design decision read from the other end, and it means the usual upgrades bite harder than they would elsewhere. Fitting 265/75R16 makes a 3.909 axle behave like 3.78 and a 4.30 like 4.16. Going to 285/75R16 takes them to 3.64 and 4.01. The 4Runner's single 3.727 becomes 3.60 on the smaller of those two steps.

A truck that started deep has room to give some of it back, which is most of why these platforms tolerate large tires without the drivetrain arithmetic becoming absurd. Whether any individual vehicle should give it back is not a question a size code can answer.