I've read the threads about gearing ratios and the more I read the more I wonder what to get. I'm looking for the max benefit from the ecodiesel, mainly my latest decision to go with a diesel truck this time around. The confusion is in wheel size paired with gear ratio and what type of economy comes from it. The truck will mostly be used on highway/turnpike driving in sunny south flat ass Florida with minimal around town driving, lets say 80/20, not really ever towing anything or heavy loads. Someone who is more savvy with this could possibly explain the differences with 17 vs 20 wheels paired with gear options. All of this is obviously dependent on the right foot's cooperation but consciously thinking about fuel savings and using cruise control as much as possible should help. Thanks for an explanation even if this horse has been beaten way too many times.