This tire sealant dipstick isn’t quite as dumb as it sounds

The Muc-Off Hey Dipstick! allows you to check bike tire sealant levels so you know for sure when it's time to top off.

Tubeless mountain bike tires are great, and everything from rims to tape, and sealant to valves, keeps improving to make installation and maintenance easier every year. When it comes to periodically checking sealant levels, most of us just give our tires a shake to make sure there’s still some liquid sloshing around inside. For those who want a more precise measure, or just want to nerd out, there’s the $15 Muc-Off Hey Dipstick!

The CNC-machined tool is designed to measure how much tubeless sealant is left in a tire the old-fashioned way. Set your bike in a stand so the tire isn’t resting on the ground, and spin the wheel so the valve is in the 6 o’clock position. After giving the sealant a moment to settle, remove the valve core, or if you’re running Muc-Off Big Bore valves, open the ball valve fully, and insert the dipstick until it touches the inside bottom of the tire.

Though the measurement grooves on the dipstick don’t correspond to a specific volume of sealant, which will vary based on tire size, it does give you a relative measure of how much liquid sealant is inside the tire. Not only that, you can get a sense of whether your sealant is dark and dirty or thin and watery, either of which could suggest it’s time for a refresh. Muc-Off recommends using a permanent marker to note your ideal sealant level at the time of a refresh and to use that measure to gauge when it’s time to top off.

I tested the Hey Dipstick! on a number of different valves, and found it works just fine for standard Presta valves with removable cores, the new Clik valve, and naturally, the Muc-Off Big Bore valves shown here. Unfortunately, it won’t work with Reserve Fillmore valves, and though it can be used with a Stans Exo Core valve, you’ll need to remove the upper portion of the valve stack, which is a hassle.

Thicker tire sealants like Muc-Off’s own tend to show up better, and the Hey Dipstick! works just fine with thinner sealants like Stans, too. Remember to clean the dipstick well after each use, otherwise it can be hard to read the tool the next time.

Would a long toothpick or a wooden BBQ skewer work just as well? Probably. And the dipstick method isn’t the only way to check tire sealant levels. Syringes like this one from KOM Cycling allow you to add sealant, extract it to see exactly how much liquid remains down to the milliliter, and replace it without getting your hands dirty. If you don’t have a dipstick or a syringe, you can pull your tire off the rim to check the sealant level, but that’s a hassle, and it’s generally pretty messy.

Which is why most of us just end up giving our tires a shake before heading out the door.