I am going to buy the new Bfgoodrich gforce KDW2. Now if I put on 245 40 18 will they fit on stock rim, and if they do. Do I have to have ECU adjusted so my speedometer reads the mph correctly

245/40s should fit fine on the stock rims. The sidewall height will be pretty close to stock so the speedometer error will barely be noticeable.

If your stock tires would show 60mph on the speedo, the 245 40 18's would read 60.6. The 245 40 18's require at least an 8" wide wheel, which is the width of the stock wheel.

Got 245/40 18s on mine, they're great! I decided to go with that size after doing a couple searches on this forum and reading all the other posts from people who tried various tire sizes. :)

post pics if possible when you get them on there, those are the tires and the size i'll be going with when summer rolls around again.

Here's my Sumitomo HTR+ in 245/40WR18s!

http://images3.fotki.com/v25/photos/1/140558/518857/IMG_2985-vi.jpg

http://images3.fotki.com/v25/photos/1/140558/518857/IMG_2984-vi.jpg

http://images5.fotki.com/v55/photos/1/140558/518857/IMG_2981-vi.jpg