Hey Paula,
What a great questions, never thought of that, but I usually do not put towels in the heavy duty dryer, I mostly dry with medium heat and they come out more delicate. I actually tend to replace towels every now and then, but I mostly use Martha Stewart and Macy's spa selection towels that don't get so dry easily. If I was to use a particular product I would have shared. I would recommend using a softer laundry detergent (I use Clear), dry with a medium to low heat and use cotton spa towels only that don't get too hard, also replace them once in a while. Hope this helps.
Rose.