Coupling unit

A coupling unit for coupling a tire to a rim, the coupling unit comprising:

• an upper surface, a lower surface, and side surfaces,
• wherein a maximum length of the coupling unit is larger than a distance between both hooks of the rim,
• wherein the side surfaces include sliding areas that are slidable with respect to the hooks of the rim while the coupling unit is being inserted into the rim,
• wherein in a state in which the coupling unit is completely inserted into the rim, at least a part of the upper surface is in surface contact with lower surfaces of the hooks to prevent the coupling unit from being separated from the rim,
• wherein the maximum length L satisfies the following equation 1;
• L
• ≥
• (
• L
• R
• +
• P
• -
• 1
• 2
• ⁢
• h
• )
• 2
• +
• (
• H
• R
• +
• R
• )
• 2
• ,
• [
• equation
• ⁢
• ⁢
• 1
• ]
• where LR denotes a length between the hooks of the rim, P denotes a maximum length by which the hooks protrude from inner walls of a flange, R denotes ½ of a thickness of the hooks, h denotes a maximum height from the upper surface to the lower surface, and HR denotes a height of the inner walls of the flange,
• wherein the maximum height h satisfies the following equation 2;
• h≤HR, [equations 2]
• and
• wherein a minimum length l between the side surfaces satisfies the following equation 3;
• l≤√{square root over ((LR+P−b)2+(HR+R)2,)} [equations 3]
• where b denotes a larger one of h and (L-l)/2.