ddgsxr504 wrote:235/40/18 in the front and 245/40/18 in the rear. This means that your tire sidewall height will be 94mm (3.7in) in the front and 98 (3.8in) in the rear and your treadwidth for the fronts are 9.25in and 9.65 for the rears.
245/40/18 is nearly an inch larger in diameter than stock tires.
To the creator:
http://www.1010tires.com/TireSizeCalculator.asp
Use that site^ to closely match overall diameter, or to see other dimensions of the tire.
225 is generally the best fit for an 8" wheel, 235 or 245 for a 9"
Don't stagger your tires very much or it will cause lots of understeer.
This should be enough information to allow you to make your own decision.