<p>A center-of-gravity tilt-in-space wheelchair includes a base, a seat for supporting an occupant, and tracks supporting the seat for selective seat movement relative to the base. Wheels are adapted to support the base relative to a supporting surface. The tracks serve as rolling or sliding surfaces that allow the seat to rotate with respect to the base. Each track has a constant-radius arc with a focal point that is adapted to be coincident with the center of gravity of the wheelchair occupant. A low-friction supports the base relative to the seat. The low-friction support may include low friction elements that mate with the tracks to support for the tracks. The support can be adjustable to permit the overall tilt angle range of the tracks to be adjusted. The wheelchair seat can be adjusted to maintain the focal point of the constant-radius arc of the tracks coincident with the center of gravity of the wheelchair occupant. The front and rear wheels can be adjusted fore and aft relative to the focal point. A coupling includes plates having upper ends operatively attached to one another with seat canes therebetween and lower ends releasably attached relative to the side tubes. The lower ends can be movable in a longitudinal direction relative to the side tubes while remaining operatively connected to the side tubes. A base frame can include side frames having an offset at a front end and a caster housing supported by the offset. The offset is directed up to minimize the height of the side frames and down to maximize the height.</p>
