They're not 19". Given that they're level with the top of the main tube, that means they have to be closer to 28" in diameter. Compare to this - the tire is about 23" in diameter.

I think there were some issues with this not actually being possible to produce. Or, at least, in an affordable way. There's a lot more to designing a body than simply trying to draw the Lost Transformer. How would those panels come out of a mould?