I like tractors. Lots of them out around here now. A couple nights ago I was drafting an International with an empty hay wagon at 23.5 mph for a bit, then decided to try and pass. I cranked it up and went around, stayed ahead for maybe 1/3 of a mile, but tractors don't get tired. He started catching back up, but I knew where he was turning off and managed to force my legs to keep ahead of him. I was only about a 1/2 mile from home, and my legs were smoked. I couldn't even walk into the house, had to sit next to the bike for a bit. BTW, combines are the best to draft behind, and provide the most motivation to stay way in front of them.