Offset is one of the most confusing aspects of wheel fitment.
Put simply it is where the center of the tire sits in comparison to the point where the wheel mounts to the car.
But to make it as simple as possible the lower the offset the more it sticks out. When you add spacers this lowers your offset even more. So a 8mm spacer on a et 45 wheel, now has an effective offset of et 37. It is pretty simple. But if you have more questions feel free to contact us.
If you are looking for help figuring out if a certain set of specs will work on your car? Try our Fitment Helper. Will they fit also provides another excellent wheel fitment visualizer that can be found here.