DIN relays (1" cube) are rated for 30A typically, but I've seen some at 40A.
Mini-DIN relays (the ones you're probably talking about - they're about 2/3 the size) are usually good for 15A each, IIRC. I'd have to look to be sure, but that sounds right (I'd probably not push them past 10A.)
Figure circuit load by taking the nominal wattage and dividing by a nominal 12 volts - the answer will be in amperes. Bear in mind that "nominal" voltage is somewhat lower than "operating" voltage - thusly:
"Nominal Design" voltage is 12VDC.
"Nominal Operating" voltage is 13.0-13.6VDC (depending on who you talk to.)
"Actual Operating" voltage is usually ~14.0VDC (varies by system and load.)
Given a specific power rating (Watts,) an increase in operating voltage results in a decrease in operating current, as in:
65W @ 12.0VDC = 5.4167A
65W @ 13.0VDC = 5.0000A
65W @ 13.6VDC = 4.7794A
65W @ 14.0VDC = 4.6429A
So, if you design for a nominal voltage of 12.0VDC ("nominal design") you'll be building in a comfortable margin. Thus:
2 x 65W = 130W @ 12.0VDC = 10.8333A. Therefore, your full beam circuit should be designed to handle a current of 11A in total - the mini-DIN relay will handle that fine. For your dip beam, 2 x 55W = 110W @ 12.0VDC = 9.1667A, design for 10A maximum draw.
Make sense? Using mini-DIN relays will allow you to run a simpler spares box, but it's a cinch you're also using full-size DIN relays in your rig - so you should keep those around anyhow. Might as well design for full-size DIN relays - since that gives you more room for upgrading later.