245/35/20 and a 20x8.5 wheel is ideal. if you are planning on a drop then you dont want to go any wider than 8.5. trust me. you will rub.I got 18's on it now but tink they are too small and want something bigger. thinkin 20's. but i dont know what size tires i should use or what the biggest tire i could use on my 2006 altima.