[masraum]

As stated, it's going to depend heavily on the vehicle.

The offset could impact if you get fender rubbing or rubbing on the suspension. You could have tons of space to change the offset without any impact at all or you may have very little wiggle room. You may be able to change the offset and then compensate as asphalt gambler said. Or maybe you want the wheels to stand out a bit more to be closer to flush or even stick out of the fenders a bit.

Depending upon the vehicle, you may be able to find folks that have strayed from stock sizes to get more info without needing to perform trial and error.