Upsize 2017 CTS-V tires?
 

I need to mount snow tires and want to go from 265s to 275s which are only .3" taller (not an issue)/.15" greater radius but they are .5" wider (.25" out each side) and I do not know if I have even that 1/4" clearance to my fender. Anyone have real knowledge that can assist me? Please no comments suggesting I should not or you would not do this. I seek usable info. thnx !!!

If your tire size is different than stock your spedometer will be off becuase the rotation distance will be different.