Tire upgrade options for 2018 Mazda6? Suggestions please!

All - Recently picked up a lightly used 2018 Mazda 6 GT Reserve. Giving a serious thought on upgrading the tires to 255/40 R19 from the current 225/45 R19. I may have to replace the wheels as well as the stock wheel only has 7.5" of width. What would be ideal wheel size to look for? Will the R19 / 8.5 will be good enough for the 255/40 section tires? Also, is there anything else I need to be worried about ?

Suggestions please.
 
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