OK, let's try this. With your 0 - 5 pound scale, weigh each wheel separately with the plane fully assembled then add the three readings together. To do this properly, you will need to prop each wheel up to the same height as the one being weighed. If your scale is, say, two inches high and you are weighing the right main wheel, prop the left main and the tail wheel up two inches. Record all three weights and advise. BTW, this is the way full size planes are weighed.