Anyone know what the highest aspect ratio tires you can run on the Medusa's? I think they recommend 225/45's and I'm looking at maybe 225/55's.

 

55's will through off your speedo. You should be able to have your local dealer correct it for you.
Other then that, they should work just fine as long as you're at stock ride height and especially if you have an AWD model... Lol

 

What are your thoughts on 225/50's then?

 

I have been running 225/40/18's on my 2005 V50 for about 50K miles. No problems whatsoever. Eagle F1 GS-D3 for 40K miles, and now Nitto Invo for 12K.