What is the largest suspension lift kit?

It depends if you want a bolt on kit or a custom kit, the largest bolt on kit is a 24" Full Throttle supension kit for a 99-04 F-250, F-350, and Excursion, you can fit any size tire underneath it. then you have the custom lift kits, the largest recorded on a street legal truck is a 52" lift with 54" boggers. I personally own an Excursion with the 24" lift kit, and I own an 01 Dodge 1500 with 14" suspension lift with a custom 4 inch body, sitting on 49 iroks.