Tire Fluids

Submitted Article
Tire Fluids
by Curtis von Fange

It came as a surprise. The tire on the tractor needed to be pulled off to get to the brakes for service. The tires were blocked, the rear end raised on jacks, the lugs loosened and the tire loosened from the hub. Then, as the big lugged circle of rubber slipped off the last wheel stud it became apparent that there was more there than just an empty tire. Four hundred pounds of rim, tire, and fluid dropped to the ground like a sack of wet cement. Fortunately the installer jumped out of the way in time to avert a dangerous disaster. So what was this stuff in the tire and why was it there?

Long ago farmers discovered that by adding weight to a tractor certain benefits were recognized. One of those benefits was traction. When pulling implements like a plow or heavy disk through the ground the added drag often caused the tractor tires to spin. By adding weight to the pulling unit the tires could pull more of the tractor weight without loosing the traction. Some farmers installed counterweights on the front of the tractor such as one hundred-pound slabs of steel bolted to the frame. This helped to hold down the front end of the tractor when rear wheel spin would actually raise the front end off the ground due to the implement drag. Others added fluid to the tires. This would increase the overall tractor gross weight which could also increase the amount of draw bar pull by delivering more engine horsepower to the ground through the wheels. In addition the extra tire weight also increased the traction characteristics of the tire by burrowing the tire lugs deeper into the ground with better holding capacity. Fluid added to the front tires helped hold the front end down while pulling large loads, especially on hilly terrain where the front end would tend to bounce off the ground.

The fluid added to the tire inner tubes is simple water. That is why it was so popular to use when extra weight was desirable. Water was cheap and plentiful. The only problem was that it froze in the winter time. In order to keep this from happening the farmer started to add antifreeze solutions to the water. The more expensive types of antifreeze that were used included alcohol and ethylene glycol. These worked quite well but with the potential of running an ever so common briar through the tire and losing the liquid onto the ground a cheaper and simpler solution was used. Calcium chloride became that more attractive solution since it was easily obtained at a cheaper price. It came in powder form and was mixed with water which was then pumped into the standard tire inner tube with a small reciculating pump and valve stem adapter. When a weight mix of 29.8% was used then the eutectic temperature, or the maximum temp that the freezing point of water can be depressed, is around minus 60 degrees Fahrenheit. This type of mix was usually found in most weight based fluid filled tractor tires. Water was put into a barrel or container then the calcium chloride was added and thoroughly mixed. Then the tire was filled from half to three-quarters full, depending on the desired weight to add, then topped off to the standard pressure rating with air.

One negative aspect of using the calcium chloride is that it is quite corrosive. This can be noticed by the corrosion and excessive rusting around tractor rims where the fluid has leaked out of pin holes or leaky valve stems in the inner tube. But with some simple care in filling, repairing leaks, keeping rims primed and painted, and simple washing off of leakage areas this problem can be readily circumvented. Be certain that if the tire encounters a leak that when the tire is removed from the rim it is thoroughly washed to remove the calcium chloride residue. Both the rim, tube and inside of the tire should be rinsed. Another aspect to be aware of is that the extra tractor weight will tend to pull more equipment but it will also sink deeper in soft ground. Yes, the traction will be there but if the soil is too soft to support the total weight the tractor may bottom out on the drawbar and leave the wheels spinning. Either way, be cognizant of the ground conditions before trying to plow, disc, or bushog in wet land.

Calcium chloride is still used in tractor tires today for adding extra weight and traction to the tractor. A tire store that services farm and/or industrial excavating equipment would be a good place to start when looking for a business to fill this need.

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