Run-flat tire system

A run-flat tire system comprising a tire and a tire core disposed therein,

• the tire comprising a tread portion, a pair of sidewall portions and a pair of axially spaced bead portions with a bead core therein and having a toroidal shape,
• the tire core being an annular body of an elastic closed-cell material,
• the radially outside and inside of the tire core each provided with a circumferentially extending groove,
• the radially inner groove extending radially outwardly beyond a bead core line, the bead core line defined as a straight axial line drawn between the centers of the bead cores,
• and wherein when the tire is mounted on a standard rim,
• the radially outer groove forms a radially outer space extending circumferentially of the tire and having a cross-sectional area of from 1 to 6% of the total sectional area of the tire cavity, and
• the radially inner groove forms a radially inner space extending circumferentially of the tire having a cross-sectional area (Si) of from 10 to 25% of the total sectional area (S) of the tire cavity.