What does 1721 on tires mean?

[Humbert]

Tire 1721 means the production date is the 21st week of 2017. Here is the relevant introduction about car tires: 1. Definition of tires: Car tires are one of the important components of a vehicle, directly in contact with the road surface. Together with the car suspension, they cushion the impact during driving, ensuring good ride comfort and smoothness, maintaining excellent adhesion between the wheels and the road, and improving the car's traction, braking, and off-road capability. 2. Phenomenon of low pressure: Air pressure is the lifeline of a tire. Both too high and too low pressure will shorten its service life. Low pressure increases the deformation of the tire body, easily causing cracks on the tire side, and generates flexing motion, leading to excessive heat generation, which accelerates rubber aging, fatigue of the cord layer, and breakage of the cords. Low pressure also increases the tire's contact area with the ground, accelerating wear on the tire shoulders.