The larger hub bore is just so the wheels will fit on more than one make of vehicle. They use the lugs to center the wheel on the vehicle (lugcentric) vs. stock wheels which use the hub on the vehicle to center the wheel (hubcentric). Because the aftermarket wheels are lugcentric they might not get centered as perfectly as a stock OEM wheel. This can cause vibration very similar to out of balance tires/wheels. If you have this issue you can use some hubcentric spacers. They fit on the hub on the vehicle and increase the diameter of the hub to the bore of the wheel. I had this issue with the alloys that I have, not sure if people have this issue with these steelies.