Id also agree you need an enclosed trailer, 6'x12' would be the better size to start with if you can afford it, and they can be pulled with your car if you arent hauling a whole lot of stuff in it. With just one kart, one engine, and other random things like gears and tires, tools, i wouldnt think you would overload your car capacity with a small trailer. Id agree that anything over 12' or more than one kart in the trailer and you would want a truck to pull it with. i started out with a 6x12 trailer pulling one kart, one engine and a few sets of tires, with a regular cab ford f150 pickup truck. Iv upgraded this season to a nice 8'x14' trailer with about 10 sets of tires, several engines, one kart, and alot of tools and extra equipment, and that same F150 pickup still pulls the 14' trailer just as good as it did the smaller 6x12, and cant hardly even notice it being back there.