Will 255/35/18 tire fit on a 18x8 rim? Some tell me no others tell me yes can anyone please let me know

will it fit? yes. Is it optimal? no.

if it fits then why is it not optimal

It will not look too good. My 2cents :D

255 is made for a 9inch wide rim. 8 I woudln't put anything bigger then a 245. but I would run a 235 for max performance in my mind.

Yes, it will fit. Its not much of a stretch.

Again yes no answers So they will fit, is there any chance of the tire coming off from stretch or flex during hard driving will it grip right?

I've been thinking of running a 255 on a 8.5 in the future would there be any problems? Also would a 235 work on a 8.5?