i visited a few tire shops in T&T asking about going from 205\65\15 to 205\50\17 all said "go with 45 series cause it go rub or touch"
only d owners daughter in wheel wizard actually calculated it & told me yes 50 will work since outside diameter is near identical , she said she thinks why others say 45 cud be cause to some ppl a 17" rim with a 50 series tire looks too fat so most want a "low profile look" with d 45 tire
according to tire calculators i type in online all said 50 series was fine .....