as good as it sounds, to have a formula for all tundras, this is probably not possible. Keep in mind not all trucks are created equal. If you go to the dealer and measure the clearances, you'll see a difference between RCSB, DC, and Crewmax. Also, there will be some variance between like makes of 4x4 and 4x2, and probably even between identical vehicles. Throw in weight differences between engine choices and you'll get a whole different set of data according to some on this forum. Finally - look at manufacturers tire sizes and a 325/60r20 by BFG is different than the same size by nitto, etc. Good luck.