Tire Size vs Wheel Size: How to Read a Tacoma Tire

What do the numbers in a tire size like 265/70R17 mean?

A tire size is four pieces of information packed into one code. Reading 265/70R17 left to right: 265 is the section width, 70 is the aspect ratio, R is the construction type, and 17 is the diameter of the wheel it mounts to. Only that last number describes the wheel - everything before it describes the tire.

An optional load index and speed rating often follow the diameter, such as 265/70R17 115T, where the number is the load index and the letter is the speed rating. Light-truck tires add an LT prefix (for example LT285/70R17) and a load range letter - C, D, or E - that sets the maximum cold pressure. Tacoma original-equipment tires carry a load index of 109 or higher.

Is the rim size the same as the tire's height?

No. The rim diameter is only one of three inputs into how tall the tire actually stands. Overall diameter in inches equals the rim diameter plus two sidewalls: rim + 2 x (section width mm x aspect / 100) / 25.4. For 265/70R17 that is 17 + 2 x 7.3 in = 31.6 in. Change the width or the aspect ratio and the height changes even though the wheel does not.

This is why two tires on the same 17-inch wheel can be very different heights. A 245/70R17 stands 30.5 in tall, while a 285/75R17 stands 33.8 in - a 3.3 in difference on an identical wheel. The wheel size tells you what the tire bolts to, not how big the tire is.

How can a 17-inch wheel run a taller tire than an 18-inch wheel?

Because the sidewall does the work. Overall height is the rim plus two sidewalls, so a smaller wheel simply leaves more room for sidewall at the same total diameter. Hold overall diameter near 31.6 in and drop the rim size, and the sidewall grows to fill the gap. That extra rubber is exactly what off-road builds want.

Now pick tall sidewalls on a small wheel and short sidewalls on a big wheel and the smaller wheel wins outright on height. A 285/75R17 stands 33.8 in; a 275/55R18 stands only 29.9 in. The 17-inch setup is 3.9 in taller than the 18-inch one, even though its wheel is an inch smaller - all because of the sidewall.

How much sidewall does each rim size leave at the same tire height?

The tables below hold the overall diameter steady at four heights Tacoma owners actually shop - stock-class, a true 33, a 34, and a 35 - and list the common sizes on each rim from 16 to 20 inches. Every number is computed from the size code with the same math as the tire size calculator. Sizes marked "Tacoma size" have their own Tacoma size page on this site; "geometry only" rows (265/55R20, 275/60R20, 295/60R20, 315/75R16, 35x12.5R18, and 35x12.5R20) are here to show the shape of the trade, not to suggest they fit a Tacoma.

What the four tables say, in sentences you can check against the rows:

• About 31.6 in (stock-class): a 265/75R16 on a 16 in rim has 7.8 in of sidewall, while a 265/55R20 on a 20 in rim has 5.7 in - 2.1 in less rubber on each side of the wheel.
• About 32.8 in (true 33): a 285/75R16 on a 16 in rim has 8.4 in of sidewall, while a 275/60R20 on a 20 in rim has 6.5 in - 1.9 in less rubber on each side of the wheel.
• About 33.8 in (34-class): a 285/75R17 on a 17 in rim has 8.4 in of sidewall, while a 295/60R20 on a 20 in rim has 7.0 in - 1.4 in less rubber on each side of the wheel.
• About 34.9 in (35-class): a 315/75R16 on a 16 in rim has 9.3 in of sidewall, while a 35x12.5R20 on a 20 in rim has 7.5 in - 1.8 in less rubber on each side of the wheel.
• At the same overall height, every inch of rim diameter costs between 0.45 and 0.52 in of sidewall on each side of the wheel.
• A bigger rim does not make a taller tire: the 265/55R20 on a 20 in rim is 31.5 in tall, no taller than the 265/75R16 on a 16 in rim at 31.6 in.
• Section width comes from the first number in a metric size, not the rim: 265/75R16, 265/70R17, 265/65R18, and 265/55R20 are all 10.4 in wide.
• At stock-class height, a 20 in rim keeps 73% of the sidewall a 16 in rim carries.

What is the difference between metric and flotation tire sizes?

You will see two labeling systems on Tacoma tires. Metric (P-metric or LT) sizes like 265/70R17 give width in millimeters, sidewall as a percentage, and rim in inches. Flotation, or high-flotation, sizes like 33x12.50R17 give the overall diameter in inches, the section width in inches, and the rim in inches. Flotation sizing is common on aggressive all-terrain and mud-terrain tires.

• Metric: 265/70R17 - width 265 mm, sidewall 70% of width, 17-inch rim. The first number is width, not height.
• Flotation: 33x12.50R17 - about 33 inches tall, about 12.50 inches wide, 17-inch rim. The first number is height.
• Flotation numbers are nominal and rounded: a labeled 33 often measures closer to 32.5 inches, and the stated width applies at a specific rim width.

How does wheel size change ride, air-down, and rim protection?

At a fixed overall diameter, a smaller wheel means more sidewall and a larger wheel means less. More sidewall flexes more, which softens the ride, airs down better for traction off-road, and shields the wheel lip from rocks and curbs. Less sidewall sharpens on-road steering response but exposes the rim and rides firmer. This is why 17-inch wheels are the popular Tacoma off-road choice and 18s or 20s lean toward street use.

How do I read my own Tacoma's tire size?

Your factory size is printed two places: the tire information placard on the driver's door jamb, and the sidewall of the tire itself. The placard also lists the recommended cold pressure. Current Tacomas ship in several sizes by trim - 245/70R17 on SR and SR5, 265/65R18 on TRD Sport and Limited, 265/70R17 on TRD PreRunner and Off-Road, and 265/70R18 on the 2026 TRD Pro and Trailhunter (Toyota describes the 2024-2025 versions of those two only as a 33 in tire on an 18 in wheel) - so confirm your own rather than assuming.