Runflat system for a motor vehicle

A runflat system for a motor vehicle, the system comprising a non-standard one-piece rim having at least a first peripheral cavity or drop center to enable a tire to be mounted on the rim and a second peripheral cavity separated from the first cavity by an intermediate peripheral ridge, and a runflat device for mounting on the rim inside the tire, said runflat device being constituted by a rigid ring split into at least two circularly arcuate elements or sectors, wherein each sector has a radially inner portion for being received in the second cavity, the system also having means for fixing the sectors in the second cavity of the rim, wherein the means for fixing the sectors of the ring on the rim comprise at least first means for taking up lateral forces tending to move the sectors laterally inside the second cavity of the rim, and wherein these first fixing means are constituted by spacers suitable for penetrating into the second cavity of the rim in order to engage between the intermediate ridge and at least one sector of the ring so as to act as a wedge and prevent the set of sectors of the ring from moving laterally inside the second cavity of the rim.