Interesting read - here and here

Most will know that it's generally best to have your better tyres on the rear, but in a lot of situations, it is more advantageous to have them on the front!!! But in the more critical situations, you'll be thankful they are on the rear!

There's not a whole lot those of use with staggered sets up can do, but obviously its best to rotate the tyres every few 1000 miles