there are so many things it could be that it would be impossible to address it all in a post. Usually its how you handle the dough, or under or over proofing, mixing too long..... but there are many other things that can contribute to a tough crust. Just wondering, I noticed this was posted in the neapolitan thread. Is it possible you were using caputo flour? If so that flour produces a chewy product unless your bake time is under 2 minutes. A bake that fast is hard to do, even in many wood burning ovens. The ovens in naples using caputo and other 00 flours are often clocked baking the pizzas in under a minute.
If you give us a post with lots of details we could help.