I would like to change my Dunlops for a something better ie with some grip and the general consensus of the HD community seems to be Avons are the ones to go for. My problem being my bike (2006 Street Bob) is fitted with Typhoon Wheels, 17" rear and 19" front. I'm guessing this is a non standard size as all the other tyre manufacturers with the exception of Dunlop, do not seem to have a rear to fit this size wheel, the current tyre being Dunlop 180/60 B17 no one else seems to have one in this size! Or can I safely fit a different size as long as it's 17" ie narrower 170/55 which is available from other makes?