Q: Are the 15 mm and 20 mm spacers hub-centric, and will they cause vibration?

They use a Tesla-specific hub-centric profile, which centers the wheel on the hub rather than on the lug studs, so they run vibration-free when installed correctly. The 15 mm front and 20 mm rear sizing pushes the wheels out to fill the fenders at the milder ride height. If you want just the spacer effect without the drop, the standalone Model 3 and Model Y hubcentric spacers are sold separately in several widths.