Slime's 5-50 PSI air/water tire gauge is a great option for checking your ballast tires! It is built with the accuracy, consistency, and dependability that you know from Slime's tire products, but this model can also measure the liquid PSI of tires. It comes in a standard pencil shape, and it includes a built-in pocket clip. | Slime 5-50 PSI Air/Water Tire Gauge