well from the pic i have i cant see if they are flat.. wich i presume they are. and now that you mention it, it never crossed my mind.. but once i have the base done you wont see the bottom of the tyres so they will prob stay as is.
here is an Up date that been long over due. 
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as you can see on this pic i broke part of the frame that holds one of the side doors, ill fix it 
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