Today, I had a helper (who wishes to remain anonymous, thus the headless pictures). I started by cleaning and oiling the breast collar and traces. The harness I have was bought second hand. It had never been used, but it had been stored for several years, so it needs to be oiled and I'm working my way through oiling all the pieces.
So, to get CJ used to the tire, I started by having my helper lead CJ and I walked past him dragging the tire (because I need the exercise). I dragged it ahead of him so he could sniff it, and then beside him on both sides, and then behind him where he couldn't see it but could hear it.
Since he was fine with this, my helper hopped on CJ and I kept dragging the tire (because I need the exercise). Then, when we were sure CJ was fine with the tire, my helper dragged the tire:
CJ didn't mind pulling the tire like this, so we harnessed him up. I ground drove him around the corral while my helper put a little weight on the traces for him to pull against. He was okay with this, so we put the tire rope through the traces, but didn't tie it to them; my helper held the rope and walked along so she could let go of the tire if CJ was suddenly unhappy with it (ie. if he bolted). In this picture, CJ is objecting to pulling. He was a little confused when he felt the heavier weight against the breast collar, but I gave him a few taps with the whip and he got the idea that he was supposed to pull.
When CJ was walking along fine, pulling consistently, we tied the tire rope to the traces and my helper was free to take pictures.
I ground drove CJ for about twenty minutes. His only change in behaviour was that he shook his head a lot, as if he thought he could ease the pull of the breast collar against his chest. So, I didn't carry on too long, and I assume he'll get used to the weight as we continue to practice this.