I'm confused on figuring out the rpms before and after i do the gear swap and tires. i have 3.42s and 265s stock and i went to 33x12.5s. after a couple weeks i went back to the 265s until i regear to 410s. city driving was killing me...wierd shift points, sluggish..etc etc..but what i can't figure out is the trucks performance if the numbers make sense. the truck felt really doggy and slow of the line, and i had no clue as to which way my speedo was reading...but other traffic sure passed me right and left! :wall anyway.... according to the calculators: (Auto/OD tranny) 3.42s + 265s = 1782rpm @ 70mph ok, that's about right, if memory serves me correct. then: 3.42s + 33s = 1706rpm @ 70mph 32.8 = 1717rpm @ 70mph hmmm, why the big discrepancy on my seat-o-meter? i don't remember what rpm range the truck was cruising in with the 33s, but it took a big hit and i can't understand it. so, theoretically, after gears: 4.10s + 265s = 2136rpm @ 70mph 4.10s + 33s = 2046rpm @ 70mph 32.8 = 2058rmp @ 70mph i guess my biggest beef is why was the truck such a weeny after going up a tire size. i weighed and measured the two tires. the difference was 1.2" and 5lbs for each tire. the only thing i can think of is i didn't weigh or measure them very good - soi can do that again. i just find it wierd :-? am i missing something? or am i thinking too much about the change, and therefore psyching myself out?