i am getting a new set of rims soon, you guys know what is the best offset for 18"7.5 and 18"8 or even 18"9
i am still deciding if i should go 9 at the back, but i dont want the rims to flush out

 

You might want to post this in the The Tire Rack's Tire and Wheel Forum. It is all been posted there over the past three years. Maybe even try the advanced site search for offset and limiting the search to the tire and wheel forum will yeild the results you are looking for.