I just bought a 2017 honda accord V-6 white all options no nav. 18,000 miles. Just bought new wheels 18in x 9.5 whistler wheels tires next. Getting as large as I can put on.
going to try 255 45 18 up front and 275 40 18 in back will see how it goes.

 

A few thoughts:

• Putting 255/45 R18 tires on the front of your car will significantly impact the accuracy of your speedometer and odometer; both of which will under report (i.e. they will say you are going slower and traveling a shorter distance than reality).
• Putting a different size tire on the rear, in this case 275/40 R18 will mean your front and rear wheels will be traveling at measurably different RPMs; this in turn may play havoc with the traction control, stability control, and ABS systems.
• Beauty is in the eye of the beholder, but I would argue such a change to your car will look pretty dumb.

 

Update I put 245 40 18s up front continental extreme contact sport and 255 40 18 in back 35 offset. No problems and does not hang out from the fender.
I have pictures and will post as soon as I figure it out. Nicky new guy so will take a min. Ride is better turns quicker and I personally think it looks better than stock tires by a lot. I use an app speedometer to show real speed and thus can calculate for future reference. 10% 5% 3% or what ever.

 

side view whistler wheels 9.5 in wheels 245 40 18 front 255 40 18 back 1 of 3

side view for idea of how much the tires protrude from the car

ground view of rear tire