Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
Funny as I've used a 4.10x19 tyre on the front with no problems. What's the clearance like on the other side? you may have the spindle in the wrong way.
One of my bikes has the original tyre. Bridgstone Superspeed. 3.25 x 19. It is 93.3mm at its widest.On the bike I use most I went against fitting wider tyres and have a Avon Roadrider 90/90 19. It is 93mm wide, but has a lower height profile than the Bridgstone so looks small. But has been fine, with quick handling and I love it.
I have an Avon Speedmaster 3.25x 19 on the front of my 500 K1. Bloody luverly, handles a treat.