The CX5 with 19 inch factory wheels has a 7 inch rim width .The perfect width rim for a 245/50r19 tire is 8.0 to 8.5 inch's wide. You will due yourself no good using a 245/50r19 tire on a 7 inch wide rim. If you want to see any benefits you will need new 8.0 to 8.5 wide rims with the proper backspacing /offset to clear the body and suspension components. This is not an opinion ,it is a fact .