Hey Team
I'm looking to make my 2004 MGM opinionated (Ford CEO words) and want to put on new tires and wheels.
Right now I have 225/60r16 all the way around, but I want wider.

Can 255/45R18 go on the front? How about 275/40ZR18 on the back?

 

255/60R16 and 255/45R18 are the same width. "255" is the width in milimeters, 60 is the sidewall and 18 is rim size. If you want to harshen up the ride but improve corning, a shorter sidewall will do that. As far as a 275 fitting, I would consult a tire dealer or actually measuring a new 275 width tire to see if it clears in the rear.A 40 series tire will provide a teeth chattering ride if that's what you are looking for.
Personally, I would not mix sizes front to back.

 

Another first time poster who posted, ran and is now hiding.They probably are looking for some hand holding.

 

No not hiding or needing hand holding.
I have been looking for a bit and I may be getting these:
Drag
DR-77

• 17x7.5
• Finish: Hyper Grey
• Offset: +40mm

WITH
Riken
Raptor ZR A/S

• 255/50ZR17
• Style: Blackwall
• Serv. Desc: 101W

OR
HANKOOK
VENTUS ST RH06

• Size: 255/50R17 101W
• Style: Blackwall
• Serv. Desc: 101W