Rim and tyre sizes

Why not use original sizes for 650SS? Yours are Atlas.

I have a slightly bent frame  Dominator with 19"  wm2 rims and 1960's style tyres , I also have an Atlas with more  modern tyres and a wm3 rear rim .  The Dommy can (and does) run rings round the Atlas any day. Perhaps there are other factors in play. I would stick with standard if plu -perfect handling is important. A 19" wm3 rear  rim with the  nearest equivalent to a 3.50x19 modern tyre  is as far as I would venture.

Checkout the DSN V1 as found on this WebSite.  There is a really informative chapter that deals with Wheels Sizes, Rims and Tyres.

The very early 650 Manxman bikes were exported with both 18" and 19" rear wheels.  In Europe the immediate successor to the Manxman was known as the 650/99 or 650 Model 99.  This had 19" wheels front and rear as well as a Dominator tank and exhaust system.   The Atlas was generally sold with 18" rear wheels but many people converted these to 19".

There was a time when owners switched to 18" wheels for greater choice in tyres , others did the same in a quest to lower the seat height , Wm2 rims ARE on the narrow side and wm3 rims and wider tyres  do "look"  more modern.  Bikes with these alterations did not turn into rodeo mounts overnight  and  owners convinced themselves they did ok, ( after you have spent your money its human nature  to be unwilling to accept   you might have made a mistake).  I value the steering lightness and inbuilt tendency to drift and give warning  at the limit of grip that the orriginal settup gives . I 'm leaving highsiding to those young  guys with rubber bones . Peter Williams used drift  to run rings round everyone in the corners. Imagine being on a club ride out with him !, what a loss.

.. and 3.00 on front...

Just to throw my tupenny idea into the ring- I’ve fitted a 3.25 front Avon Speedmaster onto a 19-inch WM2 front rim on my slimline Dommie 99. I have extended the ‘legs’ of the fork brace bracket to give a bit more clearance over the top of the tyre. It seems to handle well enough for my riding style. I’ve got a 3.5 inch Avon SM on the back (19-inch WM2 rim).

Regards

Tony

If you want nice light steering fit a WM1 rim on the front with a 3.00 X19 Anon Speedmaster tyre.  If you fit a modern tyre then that will be a 90 X 90 X19 Avon Roadrunner or similar.  I presume that you have the original 7 inch forks - if you have the later wider forks (with steering lock) then the 3.00 X19 tyre does look narrow which is probably why Norton switched to a 3.25 X19 Speedmaster on the front.  To further complicate matters a different method of measurement of the tyres was adopted in the mid sixties so a 3.25 X 19 became a 3.60 X19 and a 3.50 X19 became a 4.10 X19.  On my production racing 650SS  I used a pair of Dunlop K81 Roadmaster TT100 tyres.  Alas there wasn't room for the standard mudguards.  Good luck, Howard   

I think I have a 3.25 x19 on the front of my narrow (7")  forks and a fully valenced mudguard .its close ! .the biggest issue is the tiny clearance between fork shrouds and the mudguard, its a mm or two.  

Hi Bob - Whilst I did say that 3.25 X 19 became 3.60 X 19 within the new method of measuring I do believe that because of the chunkier nature of the K81 compared to say, a Speedmaster,  something rubbed.  I have a feeling that it was that the bolts, nuts and spacers that secure the stays to the mudguard interfered with the tyre.  Memory is failing again.   Cheers, howard