OK well i cant find nitto 555s in 245/40-17 for the fronts. SO would some 285/40- 18s be good for the rear? Should i see any tire rub and how much would it throw my speedometer off?

 

A 285/40-18 is a 27" tall tire. You will be adding a little more than 1/2" to the sidewall thickness. The speedo will need to be corrected, because it will read 5% slower than actual, or read 57mph at a true 60mph.

If you allow for 1/2" of the tire sidewall to be covered by the rim flange, the visible sidewall you have now with the 285/35 is:

Front VISIBLE sidewall - 3.84"
Rear VISIBLE sidewall - 3.43"

With the 285/40 in the back, you will have:

Front VISIBLE sidewall - 3.84"
Rear VISIBLE sidewall - 3.99"