What Does 245/75R16 Mean? Tire Size Explained

A 245/75R16 tire is 245 mm wide with a sidewall that’s 75% of that width, built radial, and made to seat on a 16-inch wheel — an overall diameter of about 30.5 inches.

Every number on a tire’s sidewall is a measurement, and reading them in order tells you exactly what you’re buying. This code breaks into four parts — width, sidewall height, construction type, and wheel diameter — and once you know the sequence, any tire size becomes readable in seconds.

The format is standard on US tires and mixes metric and imperial units on purpose: width in millimeters, wheel diameter in inches. That mix trips people up, so here’s the breakdown, number by number.

Breaking Down Each Number In 245/75R16

The first number is width, the second is a percentage, the letter describes internal construction, and the last number is the wheel size it fits. Read in that order, there’s no mystery left.

• 245 — section width in millimeters, measured across the tire’s widest point, not the tread face.
• 75 — aspect ratio. The sidewall height is 75% of the section width, not 75 millimeters and not the wheel size.
• R — radial construction, the industry standard for passenger and light truck tires.
• 16 — the wheel diameter in inches the tire mounts to.

That aspect ratio is the one people misread most. At 75%, the sidewall works out to roughly 7.2 inches tall on this size. A lower ratio like 55% would mean a shorter, stiffer sidewall on the same width — which is why 245/75R16 sits firmly in the truck and SUV camp rather than the sports-car camp.

What 245/75R16 Measures In Real Numbers

The calculated overall diameter is about 30.5 inches, which is why this size gets called a “30-inch tire” in casual conversation. That single number drives clearance, speedometer accuracy, and gearing.

Once diameter is known, the rest of the geometry follows. The overall diameter feeds directly into circumference, and circumference feeds into how many times the tire rotates per mile — the figure your speedometer and odometer are calibrated against.

Those last three numbers are why you can’t swap tire sizes casually. Change the diameter and you change how far the truck actually travels per wheel rotation, so the speedometer reads wrong and the effective gear ratio shifts. The math is honest even when the fitment isn’t.

What To Check Before Buying A 245/75R16 Tire

Wheel diameter has to match at exactly 16 inches, and the overall diameter needs to sit close to your current setup. Width alone tells you nothing about whether a tire will fit.

The LT245/75R16 variant carries an LT prefix, which flags it for light truck use — heavier construction for towing and hauling loads. Same size format, different duty rating.

Before you buy, confirm three things: the wheel is genuinely 16 inches, the load rating meets your vehicle’s needs, and the overall diameter is close enough to stock that your speedometer and clearance stay sane. Skipping any one of those three is how people end up with a tire that rubs or a dashboard that lies to them. If you’re comparing specific options for this size, tested 245/75R16 tire picks worth checking can save you a shopping round.

Reading the sidewall correctly also means knowing what not to assume. The 245 figure is section width, so it says nothing about tread width. The R doesn’t stand for “rim.” And two tires can both be 245/75R16 yet differ in load range, tread compound, and speed rating — the size code only guarantees the geometry. More detail on how each figure is defined lives in this guide to reading tire sidewall markings.