brake line size

[mick53]

Here is some info on my build. 53 1/2 ton pickup. Wilwood 12.88" drilled and slotted rotors. Rear cable drive emergency brake. 4 piston rear and 6 piston front. Frankland QC rear end and leaf spring front and rear if that matters. So here's the deal. I build factories for a living and we have thousands of feet of high end stainless steel tubing from 1/4" to 1/2" in my buildings. We end up with a lot of scrap sometimes 15 to 20 feet long. Wilwood tells me I need 3/16" line for my brakes and not to use 1/4" line. I don't understand why. Same in same out? In the big picture buying 3/16" tubing wont make much difference but I just don't understand why. Any advice would be helpful. I also have pallets of fittings for 1/4". Thanks for any help.