Non-pneumatic tire

A non-pneumatic tire used in vehicles comprising:

• an inner peripheral surface, an outer peripheral surface and sidewalls;
• at least one circumferential groove positioned within said inner peripheral surface of said non-pneumatic tire, said inner peripheral surface being operable to be mounted upon a wheel rim;
• a plurality of spacers circumferentially distributed about said inner peripheral surface of said non-pneumatic tire, said plurality of spacers radially extending into said at least one circumferential groove such that said at least one circumferential groove is separated into a plurality of serially spaced, radially projecting chambers, each of said chambers having substantially the same radial cross-section from its opening to bottom, and said chambers being at an internal pressure approximately equal to atmospheric pressure;
• and
• fringe portions located adjacent both sides of said inner peripheral surface of said tire such that, when said non-pneumatic tire is mounted upon a wheel rim, said fringe portions operably engage the surface of the wheel rim;
• said inner peripheral surface of said non-pneumatic tire being operable to contact said wheel rim such that, when said non-pneumatic tire is mounted upon a wheel rim and the load carried by said non-pneumatic tire is such that until a predetermined load value is reached, only said fringe portions of said non-pneumatic tire operably contact the surface of the wheel rim, while the central portion of said inner surface of said non-pneumatic tire remains spaced apart from the surface of the wheel rim, and said plurality of chambers being communicated in series via the space between the surfaces of the wheel rim and said central portion of the tire to allow the passage of air between said plurality of chambers and further, when the load carried by said non-pneumatic tire is increased above the predetermined value, said central portion of said non-pneumatic tire above the predetermined load-carrying point operably contacts the wheel rim such that said plurality of chambers at the load-carrying point from air-tight chambers, and the load being distributed equally among said sidewalls of said non-pneumatic tire and said spacers separating said chambers positioned beneath the load;
• said non-pneumatic tire further comprising an outer rubber coat and an inner rubber coat and plies therebetween, said outer rubber coat having a greater hardness than that of said inner rubber coat, and further said plurality of spacers being composed of a rubber of less hardness than the rubber of said inner rubber coat.