AKB991

Per the World 964 article, they are using 18 x 8 and 18 x 10 ( as examples ) and advise using 225 and 265 tires respectively . This is an "easy" set up and should not be any issues w/ fitment on NB 964. Hate to admit what a complete noob i am but, my wheels are 18x8 and 18 x 9.5 (not 10 as in example )- so I understand perhaps 265 is too wide but what would be appropriate ? 255 or 250 if those even exist ? Thanks in advance.