XRAY - Model racing cars

I don't race my XT8-09. Ever. Not going to. Ever. I have way too much money in it to ever sell it and I want to turn it into an onroad parking lot basher.

I was thinking of putting buggy-sized tires on it but someone told me I would ruin the engine in doing so. But, then, someone else told me my RB .21 was better suited for a Buggy than a Truggy because of the heavy tires.

My question: Why can't I install 1/8th scale buggy tires on this thing that have street treads on them?

And, if I can't, what are used XT8-09's going for these days, in general? 50-75% of new depending on condition?

Now now don't everyone speak all at once....14 views and no one has an opinion?