For the truck:
Yeah the back seat removal was truely the first mod, did that when I first got the truck back in 2006. Never had the seat in there since, I think I will sell it and try to get a few bucks for it.
I have always used the suburban as a covered pickup truck. I always need the cargo roomm not the seating capacity.
I pulled that 3rd row seat out and has to weigh well over 100lb.
The full size spare tire and jack are always gone unless I am going on a road trip.
My yokohama 31x10.5R15 AT-S tires weigh 44lb when new, plus another 15 to 20 for the steel rims.
I am not too worried about weight on the truck because it weighs 3 tons already gets very good fuel milage and there is still room to pick up 2 or 3 more MPG with motor mods and then another MPG or 2 to be had with mild aero modds.
My biggest consern about weight when dealing with the truck is when towing and hauling.
See this in reguards to tires and weight for my truck or anyones truck before you go sticking skinny tires on your machine to "save fuel":
http://ecomodder.com/forum/showthrea...tml#post258808
With big work trucks you just cant go all out for fuel ecomony, if you can then you should think about getting a car.