What tire size should I go with 18x8

[Ironicdeltaman]

I have lowering springs on it and I want to go up one size from the stock outer diameter of the stock tire that's on the 15" rim

 

[Black Turbo LTZ]

i have lowering springs on it and i want to go up one size from the stock outer diameter of the stock tire that's on the 15" rim

225/40/18

 

[mitdr774]

I have lowering springs on it and I want to go up one size from the stock outer diameter of the stock tire that's on the 15" rim

Exactly what are you trying to do?