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Pneumatic tire having a pneumatic safety insert with beads

  • US 4,153,095 A
  • Filed: 09/14/1977
  • Issued: 05/08/1979
  • Est. Priority Date: 09/14/1977
  • Status: Expired due to Term
First Claim
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1. In combination, a pneumatic tire and a wheel rim upon which the tire is supported, said wheel rim having an axis and an annular support surface extending laterally in the direction of the axis and a pair of axially spaced apart annular flanges joined to and extending radially outward from said support surface, said tire having a pair of axially spaced apart annular beads each in engagement with one of said flanges and the support surface with a pair of sidewalls each joined to and extending generally radially outward from the beads, and a tread joined to the radially outward ends of the sidewalls, said tread and sidewalls having continuous inner surfaces such that said tire and said wheel rim support surface form a closed toroidal tire cavity, a generally toroidal shaped hollow pneumatic insert member disposed within said tire cavity on the support surface of said wheel rim to define an insert inflation chamber inflatable to a first predetermined rated inflation pressure and a tire inflation chamber in said tire cavity between said tire and said insert member, said insert comprising, a generally toroidal shaped hollow member having a pair of annular insert beads, each said insert bead being axially spaced apart a predetermined amount on said support surface, said insert having an unconnected open portion between said insert beads, said insert beads having a diameter greater than the diameter of the support surface, a pair of insert sidewalls, each joined to and extending generally radially outwardly from said insert beads and an insert crown portion joined to the radially outward ends of the insert sidewalls, the sidewalls of said insert having inner and outer wall surfaces and an annular flap portion joined to each said outer sidewall surface of the insert between the insert bead and the insert crown and extending beyond each insert bead a predetermined amount for tucking between the respective insert beads and the wheel rim support surface to overlay the support surface, the flap thickness and insert bead diameter being predetermined to ensure formation of a leak-tight seal between the insert beads and the support surface when respective said flaps are tucked between respective said beads and the support surface, said insert inflation chamber being noncommunicable with said tire inflation chamber to permit said tire inflation chamber to be pressurized to a second predetermined rated inflation pressure different from the first predetermined rated inflation pressure of the tire, said insert member having a radially outward crown portion spaced from the inner surface of the tire tread where the tread contacts a road surface, said tire having a no-load section height measured from the road contacting tread portion to the wheel rim flange when the tire is at said second predetermined rated inflation pressure and not supporting a load, said tire having a rated load section height measured from the road contacting tread portion to the wheel rim flange when the tire is at said second predetermined rated inflation pressure and is supporting its rated load, and a run-flat section height measured from the road contacting tread portion to the wheel rim flange when the tire air chamber is deflated and said insert air chamber is at said first predetermined rated inflation pressure, said insert having a predetermined size range relative to the tire wherein the difference between the no-load section height and the run-flat section height is approximately 43% to 64% of the no-load section height.

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