Spiked vehicle pneumatic tyre - has separate inner and outer air chamber inflated or deflated to extend spikes

摘要

The tyre carcase has radial reinforcement inlays which form an inner air chamber (7) separated from an outer air chamber (8) by a flexible wall (6) and forming an air seal between the two chambers. The spikes (4) are anchored to the flexible wall at enlarged fixing points (9). Return springs (10) are fitted between the outer reinforcement layer and the flexible wall. The inner air chamber is inflated, either by a separate valve or in conjunction with the main pneumatic chamber (11) to press the spikes into action. The spikes are retracted when not required by deflating the inner chamber (7) assisted by the return spring (10).