Always use wire rated for the job. Lights in trucks run on 12vdc and pull more amps than in your house because of the lover voltage. two lights @ 55 watts is a little over 9 amps. That would be a minimum of 16gauge wire. I had a buddy start his truck on fire because he used the wrong wire ( plus he was a dumb a$$). Always use a fuse, and if it blows there is a reason why and fix it.
Sorry for rambling, don't wont to see people get hurt. I am an electrician and I have seen some big mistakes that have cost people big $$$$$$$ and do not want that to happen to anyone here.