I'm going with the marathons for now and my trailer is heavier than yours. I'm watching the air pressure closely and balanced the tires. I will keep the weight to a minimum and put the load of family items in the back of the truck.
I'm not using a weight distribution hitch on my truck so that should also puts less load on the tires. I also have the trailer parked in the garage to prevent sun damage. If there is room to clear the garage I will get 15 inch rims, but for now I'm living with the 14 inch rims. I'm also going to look into a tire monitor. I'll keep you informed of my experiences. Robert
www.etrailer.com/faq-weightdistribution.aspx talks about weight distribution loading.
http://www.discounttire.com/dtcs/inf...rTireFacts.dos has good info on trailer tire maintenance and life.