From the looks of the tire tread pattern, it's a Michellin, as I run them exclusivley on my bike.
My question to you, how old are these tires? The amount of tread remaining could be half way, but the real question, how old?
Check the sidewall, it should contain a four digit number, IE 2109 meaning manufactured on the 21st week of 2009. FWIW, I experience similiar cracking from time to time, but at the very end of the tire life.
Check out my review in the tire tech forum, I post pictures of my tires before every replacement.