Track system for traction of a vehicle

A track system for traction of a vehicle, the track system comprising:

• a track for engaging the ground;
• and
• a track-engaging assembly for driving and guiding the track around the track-engaging assembly, the track-engaging assembly comprising:
• a drive wheel for driving the track;
• front and rear idler wheels spaced apart in a longitudinal direction of the track system for guiding the track at front and rear ends of the track system;
• and
• mid-roller wheels disposed between the front and rear idler wheels in the longitudinal direction of the track system, each mid-roller wheel comprising a non-pneumatic tire and a hub, the non-pneumatic tire comprising an outer annular surface configured to engage the ground track, an inner annular surface opposite to the outer annular surface and facing an axis of rotation of the mid-roller wheel, a plurality of spokes disposed radially inwardly of the inner annular surface and configured to resiliently deform under loading on the mid-roller wheel such that respective ones of the spokes between the axis of rotation of the mid-roller wheel and an area of contact of the non-pneumatic tire with the track are in compression and respective ones of the spokes between the axis of rotation of the mid-roller wheel and a peripheral part of the mid-roller wheel not in contact with the track are in tension, a first lateral surface, and a second lateral surface opposite to the first lateral surface, the non-pneumatic tire comprising an elastomeric material extending from the outer annular surface to the inner annular surface and from the first lateral surface to the second lateral surface, the elastomeric material defining a plurality of openings distributed around the non-pneumatic tire and spaced from one another in a circumferential direction of the non-pneumatic tire, wherein each of the openings extends from the first lateral surface to the second lateral surface, and comprising a plurality of interconnecting members, each interconnecting member extending between consecutive ones of the openings and extending continuously in the circumferential direction between the consecutive ones of the openings, the hub comprising a material different from the elastomeric material, the non-pneumatic tire being molded about the hub.