White Wall Tyres

Alright Guys,
Im after some white wall tyres on my standard rims, anyone know how much bigger can i go, and where i can get some from?

Cheers in advance lads/girls

Check out Vespa and Lambretta scooter shops,
I'm sure I've tried 130/70/10 on the rear and 120/70/10 on the front, anything much bigger on the back and you start having to mess about with the sprocket.

Continental and shiko are makes that spring to mind.
They sell them here
http://www.t-a-s-s.co.uk/