6" Pneumatic Wheel Help/Suggestions for other wheels for an outdoors robot

[MetalJacket]

Hi everyone,

As a part of some over the summer Creo training, me, some of my team members and a few members of another team are designing a mobile t-shirt cannon to be used at school events and other such demonstrations. We know that we want it to be able to drive outside on a variety of terrains (grass, asphalt, track, etc) so we decided it would be best to use pneumatic wheels for the drive base. I have two questions; one about pneumatic wheels, and another about our decision in general.
First Question:
I was hoping to use 6" pneumatic wheels for spacing reasons however I can't tell if they are sold by AndyMark. I found the 6" hubs for a pneumatic wheel here but the only inner tube and tire I can seem to find were as a part of FIRST Choice and is no longer listed on the website. As far as anyone knows, does AndyMark still sell a tire and inner tube that fits the 6"hub? I have seen other people's suggestions on 6" pneumatic wheels from other suppliers for shooters in this thread but, if they are available through AndyMark, I would prefer to use those since that would require minimal modification of the wheels for the drive configuration we plan to use (6 wheel rocker running 1 live axle and 2 dead axles each side).

Second Question:
Do we really even need to use pneumatic wheels? We wanted to use wheels that were fairly durable that could go over any terrain one might encounter on a baseball or football field without the tread getting too torn up in the process. We chose the pneumatic wheels partly because of the cool factor (it is, after all, a demo bot ) and partly because they should give enough to kind of even out the ride as the robot goes over any bumps it may encounter. Would other wheels such as the AndyMark Plaction wheels or some kind of rubber treaded wheels provide the same performance?

Thanks in advance,
Jesse