What I am describing here is just my own positive experience, should only be considered as information and is only intended for HO scale (1:87). I take over here the NMRA standard, which says every 5 cm (2 inches)= 28.34 gr (1 once), plus 28.34 gr (1 once) on top. I do my calculation as follows. Car length of 17.8 cm, the car get the total weight of 4.5 by 28.34 gr is 127.5 gr plus/minus 5 gr. 17.8 cm divided by 5 = 3 remainder 2.8 = 3.5 units plus 1 unit makes 4.5 units. Car length of 24 cm, the car gets the weight of 6 times 28.34 gr is 170 gr plus minus 5 gr. 24 divided by 5 = 4 remainder 4 = 5 units plus 1 unit makes 6 units. So much for that of the weight. Now, to how I implement this and what I use for it. I use two materials for weighing the crs. Once roofers lead on the roll and on the other hand the selfadhesive plates which the tire dealer use when balancing the tires on aluminum wheels. Roofing lead on a roll of 1.5mm thick. Here I cut strips like the metal plate which are delivered with the car, as weight and will then stick them in their place. This results in a higher weight than the one included plate. These plates can also be left out on the other cars and then be replaced with tiles. But if a flat car or other open car (gondola) is loaded then I use the tiles that I try to hide with the load. With Boxcars it is simple to hide them. The above weight describtion refers to the entire weight of the finished car, i.e.: Car with Kadee couplings and metal wheels equipped, loading and that additional weight. Now the question; why lead or these plates? Some of us, who do use decoupling magnets under or in the tracks, know why. If there is decoupling and the weight in the car is made of iron the car gets stuck over the magnet. Oops.