tire size for 4/6 drop

[70chevc10]

hey guys, in the future i plan on doing a 4/6 drop for my truck. hopefully before winter. im curious what size tires fit under there best. right now i have 255/55/18 but i plan to switch to 20's in the future. id love to get some of the new silverado SS wheels. stock they come with i think 275/50/20 tires. those would be too tall. would i have to go with a 35? or would a 40 fit? for those of you with a 4/6 drop and 20's what tire sizes do you have? thanks.

[Robo_bot]

ya i also plan on doing that drop and that rim size im interested in what size tires everyone is running i wanna run the same 255 as 70chevc10 but 295's in the back