Need tire to tire width for C&C

[rs74]

I am in need of the outside to outside of tire measurement for the rear on an 84 C&C with duals. Looking at K30 and need the info so I can get a price on a CM flat bed. I am actually wanting to try and custom order the width of the bed so I don't have a bunch of bed overhanging past the tires. I think the standard flatbeds will have something like and extra 4" hanging over past the outside of the tires. I want it to be pretty much flush with the outside of tire. Looking at on of these beds. http://cmtruckbeds.com/pages/ss_model.html# I have to get ahold of the company in the morning to see if that is possible.