The reason I was pushing for the 235/55/17s, was because I was offered a complete set in very good shape for free. But if it's not meant to be, it's not meant to be. I decided to go with a 205/55/17 firestone to see if I can notice a difference from the stock size. I bought them, but still have to finish up the rack and pinion job, before I find out how they are.

 

Yeah those would have been too big with a 9% difference in diameter, and you would have had to check your clearance on the fenders and wheel wells. And would have affected you handling and braking, etc. Best to stick close to OEM sizes. If the 205 55r17 still don't give you the comfort, then best way to get more sidewall is to get Mazda 16 inch rims from salvage yard. Good luck.