Welcome to the world of diesel-powered "smoker" pulling tractors, where too much of anything, especially turbo boost and wheel-speed, is never enough. These are among the most incredible vehicles in all of motorsports, in any venue, on any continent, and yes, they began life as farm tractors.
We all know how the world of tractor-pulling got started. After a hard week in the fields, local farmers would get together with their horses, then as time progressed, their tractors, to see who had the most muscle by pulling a weighted sled. The theory and practice of this activity are still very much the same. Competitors pull that sled as far as they can before coming to a complete stop. It's the equipment that has been evolving at an ever-increasing rate.
One of the largest pulling sanctioning bodies in the U.S. is the ATPA (American Tractor Pulling Association), and its rulebook has provisions for several smoker classes. The introductory class in the smoker world is the "Super Farm Tractor" category. According to the Director of Operations, Kurt Johnson, "Super Farm tractor is the lowest horsepower category of the smoker classes. The tractors have to weigh in at 9,300 pounds and use the stock frame from the back of the engine block to the rear of the tractor. These things are making somewhere near 1,500 hp, and the torque is pushing the 2,000 lb-ft mark." It is important to note that the tractors in this class began as stockers that, according to Johnson, can weigh as much as 18,000 pounds from the factory. The fact that these guys are reducing their weight by nearly 50 percent is pretty amazing. Other restrictions in the Super Farm class include stock cylinder heads, a limit of a 3-inch inlet and outlet on the turbos, and a 24.5-32 tire. And what a tire it is.
Jim Sube is the man at Firestone when it comes to pulling tires and their development. Firestone's Puller 2000HP is the dominant tire in the world of professional tractor pulling, so we gave them a jingle to get some information on exactly how these tires survive the abuse they see during a pull. Sube told us, "These tires are built incredibly strong. We have tested them to 200 mph and not had a failure." That's right, folks, a tire that weighs in at nearly 500 pounds has been tested-we can only imagine how-to 200 mph, and it holds up. "A lot of people think that these tires are like a monster truck tire and that is not the case. A monster truck tire is a floatation tire. They do not have to deal with the centrifugal force that a pulling tire does, so they are built very differently," Sube said. The main difference is in the belts. The pulling tire has many, many more belts than the monster truck tire, because if it didn't, the incredible strain of its own weight and the wheel speed of the tractor would send pieces of it into low Earth orbit. In terms of the rubber compound, Sube said, "These tires have a compound that is designed for better chipping and tearing resistance. It is very close to our forestry compound. Just about every driver out there customizes the tires to their liking, but they could be bolted on right from the factory."