285/50R20 tire size breakdown:
285 = Tire width is 285 mm
50 = Aspect ratio; the sidewall height is 50% of 285 mm = 142.5 mm
R = Radial tire construction
20 = Fits a 20-inch wheel (rim)
Key Measurements
Sidewall height: 142.5 mm (5.6 inches)
Rim diameter: 20 inches (508 mm)
Overall tire diameter: ≈ 793 mm (31.2 inches)
Circumference: ≈ 2,491 mm (98.1 inches)
Common Vehicle Types
This size is commonly found on:
Full-size SUVs
Pickup trucks
Luxury SUVs
Examples include some versions of the Toyota Land Cruiser, Nissan Patrol, and Ford F-150 (depending on trim and market).
If you'd like, I can also explain the load index and speed rating (for example, 285/50R20 116V).