[QUAD-L] Off-road manual wheelchair?

[Gail Overton]

Does anyone know where I can buy an off-road manual wheelchair that I can push 
through sand/gravel? All the manual chairs have those skinny tires that get 
stuck in anything and the knobby tire bikes are built for paraplegics that can 
use their hands. My husband cannot even drive his power chair so I need to push 
him along but would like to enjoy the outdoors with him. HELP! Can't afford the 
off-road power wheelchairs and my husband cannot drive them anyway.