Depends on what you intended use is. There are a few 17" motocross tyres out there. Can't recommend any as I don't use them.
If your game is Vinduro, then I Can recommend the Mitas 644 Army Special (was the old Trelleborg Army Special).
This is available in 17", and is road legal here in the UK. I have been using these on all my Vinduro bikes for a few years now. They are very soft and grippy, seem to last forever.
BUT, they will not be making any more. Apparently the molds have been scrapped and they will discontinue the 17" when stocks run out.