Dry cracked tires and coke syrup

Basically they ment probably harder tires...maybe not cracked from dry rot though...many say that as an expression...kinda like found these in back yard....LOL
Ok the tires I'm talking about are just that old hard and when I went to cut a few that I had they were cracked
A couple of the fastest tires i have are cracked a little from dry rot and hard as a rock...