According to national standard GB 7258-2017 (Technical Specifications for Safety of Motor Vehicles), what are the mandatory tire tread depth limits and axle restrictions for heavy trucks?

1. Steering axle tires must have a tread depth of at least 3.2 mm and must NEVER use retreaded tires; other tires must have at least 1.6 mm
2. All tires must have a minimum tread depth of 0.8 mm, and retreaded tires are permitted on steering axles if certified
3. Steering axle tires require 1.0 mm tread depth, while drive axle tires require 4.5 mm tread depth
4. Tread depth requirements only apply during the annual vehicle inspection and are not checked during roadside enforcement