It depends on the quality of the surface. Assuming it's pavement, if it's smooth and free of 'big' pebbles, then onroad cars would be fine. You can still run your onroad car on a poor surface, but it'll wear quicker from the pounding and abrasion of the rocks/dust. An offroad truck can be ran pretty much anywhere. I would not run my TC on an unprepped parking lot, so it's kinda up to the folks you're running with.
Team Associated | Reedy | Airtronics
RC Excitement: Fitchburg, MA | RC Madness: Enfield, CT | Horsham RC