Having a larger OD then stock will pretty much cancle out any acceleration benifit from the lighter rims. I don't know what your setup was before but I had 245/45 18 on my car for 15k miles and could not wait to get rid of the larger then stock OD. It really threw the planted feel of my car off. After you drive it hard let me know what you think.

 

Thank you for your input it is greatly noted. lol