I always had the problem of wear on the outer edges of my boots. after trial and error, I solved the problem by fitting half an old trainer insert, cut lengthways and fitted under my Sorbothane inserts along the affected edges. It's just a bit of hit and miss guesswork but it's been successful, my soles now last longer and I feel I walk so much more comfortably. I am also a bit heavy on my left heel, in particular, that's the first sign of sole wear nowadays but I haven't worked out how to solve this.