These tire wheel threads crack me up. OP do whatever makes you happy. I would like everyone who says tire bulge is dangerous to provide pictures of the damage. I've never seen a tire that rolled off a bead if inflated properly and taller sidewalls or a bulge will act similar as far as swaying in a corner. When trying to hook a high power car more sidewall is needed to help absorb the shock at launch, this is why drag race cars have tall bulging sidewalls!!!
The M&H have a reputation for running narrow and judging by how stretched the 275/45/18 is on my 9.5" rim I have reason to believe that they STILL DO. Hence my question about running the 325 on a 9.5" rim. I know M&H says it's a no-no.
I like a smaller wheel more sidewall look but the 305/45 is overkill in my situation. Not a fan of the huge wagon wheels with stretched rubber that are trendy right now.
Judging by the photos I found the 305/40/R18 bulges a bit but it's nothing ridiculous and IMO looks good. Especially on stock height cars that can use a little extra tire in the wheel wells for aesthetic reasons. I wish Nitto made a NT05R in that size and maybe they will eventually. Whether the 555R will hold power or not is debatable as I have read differing accounts on the web. I suspect it should be fine with 400-425whp even on the street.
Ran a 305/45/18 on a 8" wheel and got the same response from almost everyone on here. It's to wide, you can't do it, looks like shit, won't fit. I cut 1:50 60' times that way (tire on the ground) now that tire is on a 10" wheel and the car hooks the same.
I will say that in a corner with the 8" wheel you could feel it roll over and stand up on the side wall but never lost traction.