Question about offsets on rims.

[TrentS13]

Okay, I have searched this forum and search engines and asked friends about offsets, but I still do not understand the concept of the offsets on FF Drivetrains and FR Drivetrain setups.

I have Motegi MR 7 which are all 17x7, and I have read on the forums that the rear rims are like 17x7.5 or so. I am running 205/40's on them right now, but plan on changing to 215/45 in my next tire change.

How does the 17x7's affect my car's handling opposed to the wider wheel setup in the rear? If 17x7's in the front and 17x7.5 are an ideal setup, where can I find rims with those different offsets that fit a 4 lug car? Thank you.