In search of tracks and drives

I am new here. I am working on putting tracks on a powerchair (electric wheelchair). have been looking for a stock size track and drive wheels, sprockets. I have found some tracks but not the drives. I have found a couple of drives but they are steel or iron and weigh to much. I have looked into timming belts and can find pulleys but the size I need are all iron or steel. I need aluminum or plastic to keep the weight down. I am interested to know what size tracks and drive sprockets that are used on the “ZOMBY”. I have been looking at tracks, timing belts and chain. I would prefer tracks. The size I am looking for is 4" to 6" wide and 72" to 96" long. The pitch I am unsure of I belive that the smaller the pitch the smaller the radis it will require. Correct me if I am wrong. I need a drive sprocket about 8" in diameter made from aluminum or plastic. Any and all suggestions are welcome.

Thank you that is a help. I do not think I found them. I was not expectng you to have the tracks but point me in the right direction.

RobotShop currently does not carry anything in this range, and although we sell the professional robots which use larger tracks, we cannot offer them separately. You might consider Litefoot tracks (by Mattracks)- these are conversion kits for four wheel drive ATVs. Beautiful systems.