Nikko, I'm running 18x8.5, 19x9.5 Mandrus Rotec rims on my SRT-6 with the stock tire sizes.

The 225/40-18 tires on the front are really stretched on that 8.5" wide rim. I'm not sure what the widest tire that will fit on the front before rubbing, 245? 255 maybe?
255 isn't wide enough on the 9.5" rears but there's more room to go wider.

If you get the Mandrus rims you'll need different lug bolts, stock won't work. There's a thread about it here on the forum. https://www.crossfireforum.org/forum...arly-pics.html

Something I've noticed is that my car rides much smoother when the temp gets over 85. Below that the tires won't get warm enough to eliminate the flat spots from sitting. Does it get that hot where you are?

You also might consider using a SL rated tire instead of an XL to soften the ride.