With a three inch drop your gunna have to probably do alot of mods, including taking out the inner fenders hammering the firewall and rolling the finders like crazy in the front so you can turn, im on tanabe dfs in the front which sit 2.2 inches ive got a finger gap between the wheel and fender will probably be over the tire. But ya 20 by 7.5 and a 225/30/20 pirellie makes one so does bfg and nitto, and another brand but im not sure, the best thing you can do is get them put them on and then mod your fenders untill it doesnt rub. thats what i did, but plan on rolling your fenders ALOT with a 3 inch drop. Good luck its gunna look sick when its done.
You dont do fender flares because thats probably not going to fix your problem because you need to have the fender lip sit up and farther out so the tire will clear it. if you did cf fender flares they might sit out far enough but youd probably have to mod those to fit also. Since you have coilovers you can always do a 2.5 inch drop for starters and then see how far you can really go down with 20 inch wheels and still be able to drive. Thats what i would do if i were you. or just leave the coilovers at 2 inches then drop it for shows and tuck those wheels like crazy Its up to you but i bet your gunna be doing alot of modding with the fenders but id stick them on and see what ya got first.