Find a tire size calculator online to find the circumference of the original tire and then compare different sizes. If the circumferences are similar, the different size should fit. I found a calculator at:
The best tire size calculator. Use our tire size calculator to find tire size specs and suggested tire sizes. Then check prices for all available tire sizes.
tiresize.com
If you go there and enter the original size, it will even give you a range of different-sized tires that will fit.
By the way, are you trying to compare RC 300 (assumed AWD) with RC 350 F Sport or RC F?