What makes one brand of trucks heavier than the other ?

Plastics, fiberglass & other composites. Newer cheaper trucks use a lot less metal parts.
The 379 is all aluminum, the 389 is not.

 

STEEL ,thick frames

 

My truck is 21,520 lbs bobtail. I ordered extra cab/sleeper insulation, apu, heavy duty suspension, and large fuel tanks, auto tire chains and every bell and whistle that kw had. So no i didn't buy some throw away stripped down fleet truck junk.

But yes the fleets save weight with no insulation packages, light weight frames, the smallest/lightest engines, also the smallest fuel tanks seen some with one 75 gallon tank on an otr truck, driver was stopping several times a day,bare minimums as far as convenience features, the smallest sleeper they think they can get some driver to live in for months at a time.

 

My 2013 Western Star weighs close to 23,000. It's spec'd for heavy haul. 46,000 rears, double frame, 150 gal tanks, 23 gal DEF tank, 24.5 tires, insulated cab, sleeper and floor.
My last truck 2006 Century Class only weighed 18,600 lbs but it couldn't stand up to the heavy loads and the rough roads I go on, although when I first got it I was going to the U.S. so it was perfect for that.
It all depends on your application.

 

Ya exaclly!!
i got a 2012 WS. And a buddy has a FL Columbia. All you got to do is close the door on a FL then shut the door on a WS. No comparison if you ask me. It's like comparing a pop can to a bottle of baileys. Lol!!

 

Quality materials make a big difference compared to the throw away trucks.

 

A guy I know used to have a day can short wheel base Volvo with a big cam, bare bones truck, steel tanks and wheels, not big tanks at all, with fuel for a day it will weight almost a 21,000 lbs, the heaviest truck I've ever seen, generally speaking, as far as I know KW always being heavy and Liners seem to be the lightest must times, so there might be an indication of quality vs weight.

 

I guess you're all talking about dual axle trucks? Tag axles save a lot of weight. Some companies run them and haul heavier loads. Please don't think I want to run a tag axle truck, but they're one of the options on weight. I think you can run almost 50K loads with small fuel tanks and tag axles.