Amanda- your rim sizes appear to be just wide enough for these 50 series tires, but you will get a bit more sidewall flex under cornering as the tires will be "bulging" out from the rims. Lower profile tires ( eg 40, 45 series) are even less tolerant of being tucked into narrower rims and you'll find wider rims are indicated for a tire of the same width. Eg., 205/50/17 accept rims 5.5" to 7.5", while 205/45/17 suggest 6.5" as minimum width rim even though they are same width tire. You may find that the front tires rub your fenders if your car is lowered. Your speedo will show a lower speed than you are actually travelling. Check out this page to see the suggested rim widths for Yoko Tires...
Yokohama Rim Sizing