Since 225 40R 19 is backordered on just about every tire I've looked at I'm wanting to bump up in width. The shop was saying these wheels should be running wider tires anyway. He recommended 245 40R 19 in the front and 255 40 19 in the back. What is everyone else putting on the stock 19s?

I'm seeing this in several threads: 245 40R 19 front / 275 35R 19 rear

 

yes what you found in the threads is what most people put on their cars, if they decide for wider tires. it keeps the tire ratio closed to stock settings.