A curb-climbing rear wheel drive power wheelchair is disclosed having a pair of drive wheels, at least one ground-engaging idler wheel connected to the frame forward of the drive wheels and at least one anti-tip wheel mounted above ground aft of the drive wheels. Each drive wheel and an associated drive assembly are mounted to a motor support bracket that is pivoted to the frame of the wheelchair. The drive assembly is mounted such that its motor is angled upward and rearward from the bracket. The anti-tip wheel is attached to one motor support bracket such that pivoting of the motor support bracket causes vertical displacement of the anti-tip wheel.