The Tacoma 4X4 also tends to come with tires far too wide for the size truck as well. One guy I work with has a 99 Tacoma 4X4, my Ranger will climb the small hill beside work in snow with the same Dunlop RV XT(large width on the Tacoma 255/70R15vs235/75R15) that his truck won't go up unless he puts it in 4WD. Apple and oranges. Regarding a full size, my last truck 1990 D250 CTD/A-727 would go damn near anywhere I asked it to with an open Dana 70 3.27:1 gears & LT235/85R16's, tire quality and weight do make a difference in 2WD. Long wheel base, no weight in the rear and rib tread tires won't get you very far in miserable weather.
About those wide tires ... I saw a huge F350 crewcab duallie in the alley behind my gym yesterday It was spinning hopelessly away, trying to climb the tiny slope while Cavaliers, Caravans, Civics etc. pulled around it and drove away.
My old F150 RWD caused me some embarrassing moments like that in its day. I don't think I'd ever buy a RWD pickup again, unless I could pick up a used one really cheap.