Copied from the Petit website:
Tyres : ONLY Dboots tyres (front & rear) - Nanobyte tyres recommended
So yes it would appear you can use any dBoots tyre.
dBoots tyres can be bought from
www.rcdisco.com or you local model shop.
I dont think the Nanobyte tyre's are on sale yet, but would imagine something will be announced asap and they should be available on the day.