This kit has been engineered around developing and offering a top quality lift solution for Tundra TRD Pro owners. ReadyLIFT's sub assembly design features a truly innovative approach to dropping the differential. Our diff drop kit is engineered for easy installation - easiest on the market - and correctly positions the differential to maintain great CV axle and drive line angles. Our system is built around maintaining correct alignment and geometry specifications. With our 44-5860 Pro Plus 6" lift kit you can rest assured you will not be wearing out those new tires. For the rear this kit includes our time-tested OEM-style cast iron rear lift blocks and longer U-bolts with hardware. Additionally, we also include bump stop extensions all the way around as well as sway bar frame mount brackets to keep the front sway bar in a factory position. To keep you driving on those high-quality Bilstein/Fox reservoir shocks, we include our popular shock stem extensions that adjust the installed length of the shock without altering the compressed and extended length. All of this contributes to an excellent driving and handling suspension system that truly compliments your Tundra TRD Pro truck! How big of a tire can you run? We recommend 37" as the maximum on a 9" wheel with a +12 offset for the least chance of rubbing. (Front mud flaps may need to be removed depending on the tread design of the tire.)