Probably not too bad really. The stock tires are close to the same diameter, but a little wider than buggy tires. So, the width might be a little off. You can get an idea from the pic posted earlier in this thread, but here it is again for your convenience:
Personally, I think 8th scale truggy tires would make it look like a MT, which might be ok for bashing since it will offer a bit more clearance.