Tire Ballast Chart Accuracy?

[oosik]

My owners manual recommends 75% fill to allow for the air to compress. Fluid does not compress in a tire.

 

[Gary Fowler]

My owners manual recommends 75% fill to allow for the air to compress. Fluid does not compress in a tire.

75% fill is generally explained (look at fill diagrams) to be just as the liquid covers the valve stem when the stem is a top dead center. You still have lots of air above that point. I like to have the liquid covering the top of the rim so no free oxygen is exposed to the rim itself which lessens any possibility of corrosion.

Fill your tire with liquid till you get liquid coming from the stem along with some air gurgles. Don't rely completely on the fill quantities from charts other than for estimates in weight added.