Which tire? That's the million dollar question. If you follow these forums on tires it'll drive you nutz! LT's,St's,China Bombs,17.5. A lot of debate! No one buys 5th wheel tires specifically for the sand. Air pressure is the key. The tires on your camper have not quite aged out yet and as long as there is no obvious damage to them, I would make a couple beach trips with them. I assume you are a short distance to the beach? Talk to the other campers about what they have. Learn how to maintain your tires and wheel bearings. (We haven't talked about wheel bearings yet! Another Hot topic!) I always cover my tires when the camper sits. Keep correct air pressure in your tires, check them often. Don't damage them by hitting curbs/potholes. Once you have educated yourself a little on tires, you will have a better idea how to spend your money