Polaris must have been taking notes. Just picked up some parts at the popo dealer and stopped to look at the 2010 xp. They redesigned the rear sway bar. And flipped it 180 degrees. Looks like you can fit 12" wides in the rear with ease now. Kudo's to them for addressing the issue of the 09.

 

I just looked at a new 10 model compared to a 09 model and i also notice a completly new and different upper a arm so the sway bars could be flopped 180 degrees. and yes i think 12" tires will fit without a problem. also see the took off the left rear brake also on the 850s

 

Now if someone will invent a way to unlock and lock the sway bar like skyjacker has Sway Lock Lock Front View Photo