Locking a tire really might not have anything to do with the tire itself. There could have been gravel, or the tire was bone cold.

And locking a rear really isn't that dangerous either. It's something you should have had to accomplish in a motorcycle safety course.

I do it all the time. Pull into a parking lot at speed and cut to left quick as you lock it up. Like you're on a dirt bike or something! Nice half circle patch left behind.................

Was it a brand new tire? If so, be careful!!!!!!!!!!!!!!!!!! New tires have to be broken in and are slippery as hell during the first hundred or so miles.