tire pressure

I'm so excited. About to set out on my first big trip from Florida to Maine via Kentucky. I'm doing some last minute checks and realized I am confused about tire pressure.  The tires say 65 lbs and, sitting in my yard my gauge reads 55. But I know once I start driving they'll heat up.  Is the 65 psi for cold tires?  If so, how do I keep them cold while driving to fill them (or more likely adjust for the change?)  Should I just go and add 10 lbs to whatever reading I get when I get there?

I'm not a tire expert but will jump in because you  say you're about to go.

I carry a little compressor to keep my tires filled to the correct setting [65 psi cold on D range tires].  I fill them with the compressor at home before we leave and check them again the morning after each stop while I'm also checking the lug nut torque with the torque wrench I carry in the trailer.  The whole process only takes a few minutes.  

For tires, 'cold' means not having been driven on, or heated up, in the last several hours.

Regardless of what your tires are filled with, its a good idea to cross check tire gauges. The cheap gauges are notorious for being inaccurate. Also, be sure to get the gauge pressed onto the valve stem straight and hold it there for a second or two.  If you hear the sound of air leaking out during the pressure measurement the gauge will likely read low.