First..I'm ignorant of tires/thread. I'd like to understand why some tires , like Dunlop , have deep thread across the entire tire, like the tires I've always known over my many years..Car tire type thread ...Yet others, like the Avon Venom I have on my ultra, seem to be solid rubber at contact with road and have the outward grooves. I understand the grooves channeling the water out and away from center. What I don't understand is the center of the tire being just solid rubber with no thread. I look at my fairly new ( maybe 2000 miles) Avon rear tire and see, what to my old-school mind, is a 'bald tire' in the center. Maybe I'm not explaining my thoughts on these Avon tires vs a more 'conventional ' thread over the entire tire. I'm told ( had dealer look at the tires) that they are fine. Am I just too old and old-school to want to see 'conventional' tire thread?