Hi Scaly,
as ever, look back into the factory archives. 1956 Indian Tomahawk, perhaps, thanks to our hosts for the photo!
Hébergé par Imagesia, le meilleur hébergeur d'images du net !
As you see, nothing too extreme, most obvious is the upswept silencer, which you probably wouldn't need, all the tinware amidships is undisturbed and your existing back mudguard has loads of room for an 18" back wheel with a 4.00 x 18" trials tyre. At the front, if you sort that droopy front mudguard out with a slighty shorter pair of rear stays and measure clearances, you might have room for a 19" Continental front on/off road tyre used on the Watsonian-Squire trails Bullet conversions, if not just fit a larger radius mudguard and paint it maroon. Bearing in mind your new-ish centre stand was intended for bikes with 19" wheels, that will be OK, mine still works on ASBO12 with a 21" front wheel. See the picture under the Side stand topic for some idea of how the 21" front wheel and 18"back wheel look on a Redditch frame.
Of course I have not properly researched the availability of 17" trials/enduro tyres or 18"front trials/enduro tyres, there might just be something that will fit Kevin's existing wheels without being too wide for the forks or swinging arm.
A.
