You've got a couple of things going on here that are contributing to your problem.
1) It is not usually a good idea to mix brands unless you know the profiles are compatible.
(For that matter, great care needs to be exercised when mixing styles/series of tire that are same brand for the same reason - profile compatibility.)
2) I don't know if the K505 is a Flintstone compound, though it wouldn't surprise me. I do know the K505 is a bias ply tire. While you didn't say which Battlax you have up front, AFAIK all Battlax tires are radials. NEVER mix bias and radials on a bike.
Never, NEVER, NEVER!!!![/b][/u]
Your bike was designed to run radials. Don't put bias ply tires on it, even in a matched set.
You need to get rid of that K505 ASAP!
Before you hurt yourself![/size]