What Does 285/50R20 Mean? | Tire Size Decoded

285/50R20 means a tire that is 285 mm wide with a sidewall 50% as tall as it is wide, built with radial construction for a 20-inch wheel.

Buying tires without reading the sidewall code is how mismatched rubber ends up on a truck. Every number and letter does a specific job, and once you know what 285/50R20 means, every other tire size starts making sense too.

This size shows up most often on trucks and SUVs, where a wide contact patch and a moderate sidewall balance load capacity with a planted feel. The code, read left to right, describes width, profile, construction, and rim size — and getting those four right is the difference between a tire that fits and one that doesn’t.

Reading The 285/50R20 Marking, Part By Part

Each part of 285/50R20 names one physical dimension or construction detail, in a fixed order that every tire manufacturer follows.

The 285 is the section width, measured across the widest point from sidewall to sidewall in millimeters. The 50 is the aspect ratio, so the sidewall height works out to 285 × 0.50, or 142.5 mm — roughly 5.6 inches. A lower aspect ratio means a shorter sidewall and a firmer feel; a higher one adds cushion.

The R stands for radial, meaning the body plies run at right angles to the direction of travel — the standard construction on modern tires.

You’ll sometimes see a letter in front of the size, like P285/50R20 for passenger-car metric sizing or LT285/50R20 for light-truck construction rated for heavier loads.

How Big Is A 285/50R20 Tire?

A 285/50R20 stands roughly 31.2 to 31.5 inches tall and measures about 11.2 to 11.9 inches wide, with a circumference close to 98 inches.

Published specs from Nokian’s size guide and tiresize.com put the overall diameter between 31.2 and 31.5 inches depending on the model, sidewall height around 5.6 inches, and circumference between 98.0 and 98.3 inches.

Circumference matters more than you’d think. A replacement tire that is taller or shorter than the factory size rolls a different distance per revolution, which throws off speedometer and odometer readings. Staying close to the stock diameter keeps those numbers honest.

Will 285/50R20 Fit My Truck Or SUV?

285/50R20 tires are built for trucks and SUVs with 20-inch wheels, and they generally mount on rims 8 to 10 inches wide. The size alone doesn’t guarantee a fit — load index and speed rating decide whether the tire can safely carry your vehicle.

Those extra markings follow the size on the sidewall. In 285/50R20 116Q XL, the 116 is the load index and Q is the speed rating; in 285/50R20 116V XL, the V permits higher speeds. XL means extra-load construction for heavier vehicles. Pirelli’s 285/50R20 tire catalog lists models like the Scorpion Verde All Season in this size, and the Nitto Ridge Grappler 285/50R20 116Q XL is another common example.

Rim width is part of the equation. Most fitment sources recommend an 8.0 to 10.0 inch wheel for this size; mounting on wheels outside that range changes the footprint and can cause uneven wear or a strained sidewall.

Exact diameter, width, load capacity, tread depth, and maximum pressure vary from one tire model to the next, so read the full sidewall marking before comparing or replacing anything. If you’re narrowing down options, our tested picks for the best 285/50R20 tires put the leading models side by side with their specs.