Toyota Tacoma 3rd gen tire sizes and gearing arithmetic

Every factory size is the same height

The third-generation Tacoma left the factory in four tire sizes across 16, 17 and 18-inch wheels, and they are startlingly close together. 245/75R16 is 30.47 in. 265/70R16 is 30.61 in. 265/65R17 is 30.56 in. 265/60R18 is 30.52 in. The entire spread, from a base SR5 on steel-look 16s to a Limited on 18s, is 0.14 in.

That is not a coincidence, it is the point. A larger wheel does not make a taller tire; the sidewall shrinks to compensate and the rolling diameter is held. It is why every trim reads the same speed at the same road speed despite looking nothing alike, and why the truck's gearing feels identical across the range.

It also means the trim you started from barely affects the arithmetic of an upgrade. Whatever Tacoma you have, you are starting from about 30.5 in.

The step everybody takes

From 265/65R17 to 285/70R17. The diameters are 30.56 in and 32.71 in, so it is +2.15 in and 7.02% — the largest single change on this list, and the one where the speedometer stops being an academic concern: an indicated 70 mph becomes an actual 74.9 mph. Ride height at the axle rises 1.07 in.

The narrower alternative is 33x10.50R17, which reaches slightly greater height on 0.72 in less section width — 10.50 in against 11.22 in — and stays a full 2 in inside the 33x12.50R17 that the word "33" usually means. It is the choice of people who want the diameter for clearance and do not want the width at the inner fender.

Gearing, on the two recorded ratios

The Tacoma's recorded factory axle ratios are 3.909:1 and 4.30:1. On the 3.909, going from 265/65R17 to 285/70R17 gives a restoring ratio of 4.18:1 — the arithmetic that would put the engine back where it was at a given road speed. The nearest ratio sold as a ring-and-pinion set is 4.10:1.

Whether that is worth doing is not a question this page answers. What it can say is that a 7% diameter increase behaves exactly like a 7% numerically lower axle ratio, and that on a naturally aspirated engine with a tall top gear, that is a change people notice.

The 16-inch path

Owners on the 245/75R16 and 265/70R16 wheels take a different route: 285/75R16 at 32.83 in, the classic 33-inch size on a 16-inch wheel and 0.12 in taller than 285/70R17. From 265/70R16 at 30.61 in that is +2.22 in, a slightly larger step than the 17-inch route reaches — which is the opposite of what most people assume about smaller wheels.

Where these figures come from, and what is missing

Two axle ratios are recorded for this truck and the transmission ratio set is not, which is why the gearing section above stops where it does. A restoring axle ratio can be computed from diameters alone; engine speed in a named gear cannot, and the six-speed automatic and six-speed manual would give different answers for the same road speed.

Your own truck's placard is the record that matters. It states the size it was delivered with and the pressures its systems were calibrated against, and it is more reliable than any table — including this one — about your specific vehicle.

If you can source a transmission ratio set for this platform from a document rather than a forum post, the contact page reaches somebody who will add it and cite it. An omission is easy to close; a wrong figure that has been sitting on a page for a year is not.