1990 Silverado, 96 LT1-4, tremac six speed w/3.42 got 27+ mpg and now with 3.73's gets 25+.. Plus all depends not on how fast it's driven, but where it's driven, you see I built this for hi-speed as well as canyon cutting..
Today's tires are 235/70's and 275/60's on 7 and 8" rims