If you want replacmement tires of the same exact same size, the you would probably have to order from CEN. For awhile, it looked at first that the Traxxas Revo was going to go the way of the 23mm hex, but then re-verted to 17mm - this affected the market. For awhile, and you still may be able to find, the "40 series, 23mm hex drive rims." I know Pro-Line made them for awhile, and so did Integy.

I have a CEN GSR 5.0 with 23mm hex - I use a Pro-Line Wabash rim and a "40 series) Bow-Tie wheel. It is a smaller diamater overall, especially that of the Genesis. However, it performs very well, traction wise, and looks slightly awkard vs. it size and the vehicle they are mounted to. Pro-Line would also be much more built and well balanced than the original CEN tires. All depends on your surface, naturally.

Hope this helps.