51 is perfect center fronts w 11 wide.
Look for 50,51, or 52
315 30 20 front w ET45 would likely need 20mm spacer, but thats assuming 27.4 OD max and NOT lowered.
315 is a performance width
18 is performance diameter, 19 on GT350 to clear brakes.
20 eats up sidewall needed for compliance and stability of contact patch especially on the street.
21 is totally just for show.
Going above 285 on 20 or 21 would be more for show than performance.