I am thinking of purchasing 4 karts, which will require me to rent a vehicle as it is 250 miles away. I am not sure if a van will work or if I can rent a trailer, just need a idea, of how big of a trailer I will need. Any advice would be greatly appreciated.
You can stand four karts on their rear bumpers upright in the bed of a pick-up. Collapse the steering columns down and take the engines off to help on space. You can do the same with an 8' open trailer or in a 10' enclosed trailer. We haul 4 race ready karts to the track in a 14' enclosed - but it requires a rack system to stack the karts 2 high.
They won't fit sideways in your Express with the bodies on -- that's what I have and I never figured a way to get it done. Even with all the passenger seats removed, you'll only get two in the van lengthwise. Now, maybe if you pull the front and rear bumpers off, you can turn them sideways -- just maybe. Even then, you'd have to overlap them. Where there's a will, there's a way.