i went from 285/75/16 stock rims to 305/55/20. i noticed a big difference with the rims slowing me down. my guess is with the lift too a few 1/10th's.
I run 12.9 on my 20's, cut 1.74 60' time with them. I think if I went with some stock sized tires, it would be a 12.7 truck. Same tune on a similarly equipped truck ran 12.6x.