Do you have any pics of the 285/40/18 on the stock wheel and also how tall was the overall diameter? I also still have the stock suspension so a little bulge should be okay.Thats going to be too big on the stock 18" wheel. I had a 285/40/18 nitto on a the stock wheel and it buldged pretty bad. The tire I would recommend on the stock wheel is the 265/40 Mickey thompson. Its about a inch shorter than the stock tire. It doesn't look horrible if you are lowered, stock height it stands out pretty bad but they hook very well.
For me with how expensive the larger wheel DR's are Im getting a set of 15" racestars and whatever tire I want. Alot more tire options and sizes also alot cheaper tires. After the 2nd tire set the price difference between a 18-19 drag radial and a 15. The wheels will be paid for.