Many general tire/wheel size guides seem to conservatively (low side) estimate the proper tire for a given wheel width. I'd recommend checking the tire manufacturer's website to see which tires they recommend for a given wheel width.
Using the 5% oversize as a limit for compatibility with the safety systems, a 205/50R17 tire with a diameter of 25.16" means a maximum tire Diameter of 26.41" (25.16 x 1.05) before exceeding the 5% larger Diameter limit.
Here's some tire/wheel info from the Nitto website -
(I added the diameter % difference info)
Nitto 555G2 (https://www.nittotire.com/pass…ra-high-performance-tire/)
Tire Size Dia. Wheel Widths
225/45ZR17 24.96 7.0-(7.5)-8.5 w/in 5% of Diameter
225/50ZR17 25.91 6.0-(7.0)-8.0 "
255/50ZR17 27.09 7.0-(8.0)-9.0 7.6% over
Nitto Motivo (https://www.nittotire.com/pass…ra-high-performance-tire/)
Tire Size Dia. Wheel Widths
205/50ZR17 25.16 5.5-(6.5)-7.5 (Polaris Stock size)
215/45ZR17 24.61 7.0-(7.0)-8.0 w/in 5% of Diameter
215/50ZR17 25.47 6.0-(7.0)-7.5 " (This is my current model and size Front Tire)
215/55ZR17 26.26 6.0-(7.0)-7.5 "
225/45ZR17 24.92 7.0-(7.5)-8.5 w/in 5% of Diameter
225/50ZR17 25.87 6.0-(7.0)-8.0 "
225/55ZR17 26.61 6.0-(7.0)-8.0 5.7% (might get by)
245/50ZR17 27.09 7.0-(7.5)-8.5 7.6% over
Nitto actually shows that if the front wheel were a 7.5" width, a 555 G2 275/50R17 will fit, but it would be 7.6% larger Diameter than the stock size and may or may not cause safety system issues.
As far as my rear tire, I have run as large as a 295/30R18 on my stock base rear wheel. I currently run a Nitto 555 G2 315/35R17 on a Mustang 17 x 10.5 +28mm Offset wheel from American Muscle. It sits about 1.5" off-center to the left, but I have not experienced any handling issues.