Think 205/40/17 will be your best bet as a balance on size and price. Think you can get 35 but will be expensive. Falken used to do a tyre that was rounded at the edge so helped with clearance. Others like yoko 888's are very square on the sidewall i seem to remember.
Even with the tyre size ive said i think youy will still have to adjust a few bits to get them to clear properly.
They are quite a lot bigger. Rs turbo 15's with 195/50/15's have a total diameter of 22.7 inches and the 17's with a diameter of 23.5 inches and the revolutins per minute will change from 889.0 to 860.0 so this will also affect speedo readings etc as its running 29 revolutions per minute less so that will be 3.4 percent to slow and when showing 60 will actually be 62.1 mph