I made a bunch of spare-ribs yesterday (10 pounds). I put a brown
sugar/salt rub on them and smoked them in my weber. I put all the
coals off to one side, with a drip pan under the other side, and put
them all in a rib rack over the drip pan. Put soaked chips on the
coals. and put the lid on. After an hour, the coals were still burning
pretty good so I put more chips on and put the lid on for another hour
or so. Took them off and ate. They were good I guess but really
tough. Any ideas as to why this happened? Did I not cook them long
enough? or too long maybe?

I made ribs a few months ago and they were perfect. The only thing I
can think I did different was I was only making one small rack that
time.

Thanks.