Great build,perfect use of piece positioning for the windows. However, i would suggest using slightly bigger rear wheels if possible, just because it gives the moc more of that tank feel that the real tumbler has. overall tho, Excellent moc.
That is one AWESOME tumbler. There are a lot of Lego Tumblers around, but this is one of my favourites, I really like how you did the windows, and the general style of the whole creation. Great build! :)