One or two people have had problems with valves on their ScootRS tubless rims.
Mike (soulsurfer) suggested the Demon Tweeks valves, which are much better. I had them fitted at a motorbike tyre shop - HGB Motorcycles - in Ruislip, north London, just off the A40 and about 3-4 miles down from the M25 turnoff.
The guys there couldn't be more helpful and I would strongly recommend them to anyone in the area. The process involves letting the tyre down, pushing it to one side of the rim, removing the old ScootRS valve and pulling through the Demon Tweeks one.
They charged me £1 plus VAT per tyre (I supplied the valves), because the old bloke who ran the shop used to sell Lambrettas in the 60s and we had a great chat. They may charge a couple of quid more if they realise there's a lot of demand but well worth it for peace of mind. The valves themselves cost about £3.50 each. I suspect it's also a great place to have new tyres fitted on ScootRS rims.
When I spoke to the feller, I suggested to him that he might consider stocking the valves himself, plus a selection of 10" tyres and scooterists would probably travel a fair few miles for excellent and fast service (they sorted six of mine out in 1 hour).
Here's the link:
http://www.discountmotorcycletyres.com/