ReadyLift offers model specific wheel spacers designed for 07-18 Chevy Silverado and GMC Sierra 1500 6-lug trucks and SUVs with the ReadyLIFT 4" SST Lift Kit. These 1/2" quality spacers are precision CNC-machined from 6061-T6 billet aluminum for maximum strength and longevity and are HUB Centric. The ReadyLift 15-3485 wheel spacers are designed for use with the ReadyLIFT 69-3485 69-3285 69-3495 and 69-3295 4" SST Lift Kit when running the factory wheels and tires. Wheel spacers are required when using the factory GM wheels and the 4" kit to properly space the factory wheel away from the suspension. If you intend on using the factory wheels and tires with your 4" Lift Kit these wheel spacers are required to be used in order to maintain the product warranty of the lift kit. Works with both factory aluminum and steel wheels. Each wheel spacer is both hub centric and wheel centric to ensure the absolute perfect fit with your hub and wheel. You will not find a stronger wheel spacer in this size anywhere on the market. When installed the 15-3485 wheel spacer will place the outer wheel lip in line with the fender. The wheels WILL NOT stick out using this spacer. Can be used on '99-07 GM 1500 trucks or any GM truck with a 6-5.5 bolt pattern up to 2018 to resolve wheel or tire fitment issues or just to increase track width. Not for use on 2019 GM 1500. Sold as Pairs. (two wheel spacers) Quantity 2 = one pair. Made In The USA.