The cheddar I use on my pizzas is almost like a good mozzarella, but has a little more fat content. I don't think you would know it was cheddar if I didn't tell you.
When changing one thing another problem can easily happen. If you don't know what your oven temperature really are, it is hard to diagnose what is going on with your bakes.
It must be a very mild cheddar. Something I like on a pizza is half mozzarella and half muenster.
Its true that I don't have anything but the thermostat. The one thing I'm very sure of is that I can't get it any hotter beforehand.
I had it on bake with temperature to maximum for 75 min, then on broil for 15 min, then put the pizza in onto the thinner 15" stone which was on the higher shelf, and switched the oven to bake. After 6 min of baking on the top shelf, I opened it and moved the pizza onto the lower stone which is only 13" but thicker, and closed the door and turned it down to 500. 4 min later I checked it and it didn't look like the bottom was done, so I closed the door and waited 1 more min, and then pulled it out.
In general, what would cause the crust to be crispy but kind of tough to bite through?
PS: Maybe next time I'll put the big stone back on the bottom shelf and do everything on bake at max temp like I was doing. I didn't have this problem before.