[munter]

Steve, as you said, you have bought them so I think you are about to learn what you need to know.  

I think the sponge will run OKish but not that great unless you use a traction/grip additive.

This is a point I have made previously about track paint....I use an oil base enamel which gives some degree of protection if a chemical wipe down is carried out after you use said additives.
I do use it from time to time...it works.
Lots use the acrylic/latex house paint on tracks which works and looks OK but I think might be too soft to protect against cleaning chemicals if tire bite/tire glue/tire goop/tire oils have been used.

Please tell us your experience of the sponge tires....one thing, the cars will run smoothly and probably quieter too.