I need to change all 4 tyres on the 138, i am thinking of going for 205/45/16 or 205/50/16, will these fit safely on the standard rim, i;m not sure what the rim width is 6/6.5/7"? What tyre profile would be best. will the 205/50 profile be to tall or should i go with the 205/45???...............................................Cheers Gary