Minnesota Administrative Rules
Agency 171 - Public Safety Department
Chapter 7445 - PASSENGER AUTOMOBILE TIRES
Part 7445.0100 - DEFINITIONS

Subpart 1. Scope.

For the purposes of this chapter, the following terms shall have meanings ascribed to them.

Subp. 2. Bead.

"Bead" means the part of the tire which is shaped to fit the wheel rim.

Subp. 3. Cord.

"Cord" means the strands forming the plies in the tires.

Subp. 4. Groove.

"Groove" means the space between two adjacent tread ribs.

Subp. 5. Ply.

"Ply" means a layer of rubber-coated parallel cords.

Subp. 6. Sidewall.

"Sidewall" means that portion of the tire between tread and bead.

Subp. 7. Tie bar.

"Tie bar" means a transverse rubber rib manufactured into some tire treads to give lateral stability to tread ribs.

Subp. 8. Tread.

"Tread" means that portion of the outer surface of the tire that is designed to come into contact with the road surface.

Subp. 9. Tread design depth.

"Tread design depth" means the distance, measured near the centerline of the tire, from the base of the tread design to the top of the tread.

Subp. 10. Tread rib.

"Tread rib" means the tread section running circumferentially around the tire.

Subp. 11. Tread wear indicator.

"Tread wear indicator" means material molded during the manufacturing process into the bottom of tread grooves and designed to visibly disrupt the tread pattern when the tread design depth has worn to a depth of 2/32 of an inch.