I've got 26 x 10.5 x 15 ET Streets on 15 x 8 rims and they work great. That size tire on a 7" wide rim will probably not fit, however the 10" wide slick might fit. It would be pushing it in my opinion.
10.5 ET Streets are the equivalent of 9" wide ET Drags in width. True 10.5 Slicks would be like 11.5 ET Streets and I wouldn't put those on a stock rim.