I usually try to get about 1000lb of shred, thats about all i'd be willing to put on my trailer,if i take the time to pack it properly it rides well. then i always want a decent mix which could be any or all of alum,copper,brass,coils,compressors,lead,stainless steel,batteries.The shred pays for the gas,tools,blades,etc,etc. my money is in the other stuff,so i gotta get a good variety to make it pay off, have to drive 30 miles to the scrap yard.