How do you check the rear wheel bearing play when you have dual tires and spoke wheels?

Am studying diesel mecanic and am actually able to do it on front single tires with aluminum wheels by moving it from back to front and checking that the play is between 0.001 inch and 0.005 inch with my dial indicator with no sweat, but today I had to do it on the back heavy spokes wheels with dual tires. I did what I had to do and checked my play by moving the tires back to front and got 0.003 inch play which is good. Then a friend showed me a trick by hitting the tires on the bottom with his knee and it gave him 0.005 inch, but then the teacher pulled the hub spokes and pushed it and gave him 0.006 inch. I tried to follow him but it didn't move. When it did, the maximum that I could get was 0.002 inch which took me quite a while to get it. Am not as strong as him btw...so is there a trick to do it right when you dont have much strength (except building muscles because I dont have much time before the exam)?