In need of parts

[Nick]

My name is nick
I am new to the forum and am need of help. I have a 1970 chevelle and purchased a pro-touring kit complete. I am looking to achieve the staggered and raked look with the pro touring capabilities . I need help with tire and wheel size desperately . I have a 20x10 rear rim and an 18x9 front . What tire size do u recomend and will I have to roll my rear fender, also is that too much of a difference in size from front to rear? Please help,, thx