it is curb weight. it is a vehicle with all original installed equipment like spare tire and tire tools but no personal items or property. vehicle will also have all fluids topped off including fuel. no passengers or cargo are allowed. that is considered a vehicle at curb weight. if you are talking where it the vehicle should to choose the right spring. the measurements are on that sheet. if it is out of spec you change the both entire spring packs. the one you listed are just add a leafs. so you would be adding a leaf to already week springs. leaf springs are hard to find. not that they don't make them but nobody seems to want to list them for sell much. jcwhitney claim to have replacement packs from day and rockauto claims to have 4 in stock but for a 2 door model. no listing for 4 doors. you might want to call them and ask you might ask a dealer near you as well. while they carry them they want about $500 for each one so a grand is lot. i believe the part number is gm 15032521. someone out there is making them and i am sure a dealer has needed some sometime. i don't know why it seems so hard to get your hands on them like at a part store. in a city nearby call a-1 springs, that is all they do repair or build springs for vehicles. perhaps there is a place nearby you that can help. should be cheaper then a dealer. maybe around the the price of say jcwhitney pricing. look at what options are out there. when you get stock springs in there your vehicle should be in spec for the rear measurements on the spec sheet. the only other spec i can offer is what is listed as overall height and it is 69.6 inches. since the roof rack was standard equipment on the tahoe it should be assumed that it was included in the overall height.