Liquid Ballasting Guide
How Much Ballast
Firestone AG has a handy table that relates tire size to gallons of water, or gallons of water and pounds of calcium chloride, and how much ballast weight would be achieved, per tire. If you are going for a 50/50 antifreeze ballast, then simply use 50% of the amounts listed for water-only and fill the remainder with antifreeze.
You can lookup how much ballast you need here. Note that the list of tires is spread over several pages in the chart – scroll all the way to the bottom and look on the right to flip between pages. Tires smaller than 8.3-20 will be listed in pages further back in the tables.
For example, using the Firestone’s table, we see that 11.2-24 R1 AG tires, a common Kubota size for a rear tire, would each require 24 gallons of water yielding 200lbs of ballast weight. If we were using a CaCl2 solution, mix 19 gallons of water with 95 lbs CaCl2 yielding 253lbs of ballast weight. Depending on your ballast type, that puts another 400-500lbs of weight on the ground to help maximize traction!
Water or Mixed Ballast?
If you intend to operate your Kubota in the winter or where outside temperatures drop below freezing, you will need to have the tires filled at a tire shop that has the pumping equipment necessary to install a mixed solution. You can still use the chart above to determine how much mix you will need and arrange that in advance to save yourself some money. I’m not aware of any do-it-yourself pumping methods that would safely achieve the results needed, so this job is best left to the professionals. The rest of this guide assumes a water ballast is used.
For tools, you will need:
- a garden hose
- water fill attachment
- a tire fill adapter
- a floor jack
Let Air Out of Tire
Using the floor jack, raise the wheel. Remove the valve stem core from the tire and let all the air out, save for maybe 5-7 psi – just enough to keep the tire bead seated in the rim. Rotate the tire so the valve stem is in the 12 o’clock position.
Thread on the water fill attachment, attach the tire filler adapter and then turn on the garden hose. You may need to occasionally turn the water off and burp the tire. As the water enters the tire it will begin to displace the air resulting in some compression. Loosen off the hose fitting and let the trapped air escape. Once all the air is exhausted, resume filling.
You will want to fill the tire no more than 75% full with water. The 75% full mark is achieved when the water in the tire has reached the level of the valve stem as the tire is filled in the 12 o’clock position. It is a good idea to just slightly overfill the tire with water, and then holding the tire and wheel perfectly upright, remove the water filler adapter. The excess water will purge itself down to the level of the valve stem all by itself and also ensures that the same amount of water are inside each
Once water has stopped coming out of the valve stem, replace the valve core. Lower the floor jack and with the full weight of the tractor on the tire, fill the tire to the correct air pressure as indicated on the sidewall of the tire, or in your Kubota Operator’s Manual.
Water ballast is removed from the tires by rotating the valve stems down to the 6 o’clock position and removing the valve cores. The head of air pressure will force the water out of the tire. If the water is coming out a little slow after a while, simply rotate the valve stem back up to the 12 o’clock position, fill the tire with the correct air pressure, and then quickly rotate the tire back down to the 6 o’clock position.
Even with the rear tires ballasted with liquid it is not a bad idea to still use a ballast box filled with field rocks on the 3 point of your compact Kubota. If you do not have a ballast box then carry an implement (securely!) back there to add weight and stabilize your machine, especially if you have a front end loader. The neighbors might think its strange having a rototiller mounted on the back of your Kubota as you push a mountain of snow down the driveway on a 20 below day, but fear not! There are some of us out there that know you are doing it right and playing it safe!
Service Department Vic