Can You Foam-fill Mower Tires? (Yes, And Here’s How…)
What is it about mower tires that make them attract every nail and razor-sharp rock on your lawn? Is there any such thing as a mower tire that won't go flat?
It seemed unlikely at first. But while plugging my left rear tire for the second time last summer, I decided to finally look for an answer to the question that had been haunting me: can you foam fill mower tires?
Yes, you can! And it's not that difficult to do by yourself at home so you don't have to pay someone a small fortune to do it. You'll just need a foam sealant solution and a couple easy-to-find tools.
I'll explain how to do it in a moment, but first you need to ask yourself the question...
Are Foam-Filled Tires Best For Me?
Sure, foam-filled tires save time and hassle because they don't go flat. But as with everything else, there are some cons that go along with the pros.
The standout item in this list is obviously the "never have another flat" thing.
Everything else, whether pro or con, is minor. There isn't room for enough foam to make a big difference in weight, but that little extra does make for more stability.
Foam-filled tires don't flex, so less rubber comes into contact with the lawn. This reduces traction, but not by much. You may want to be careful on hills until you know how your tires' tread works with the extra firmness they'll get from being filled with foam. Since there is less tire grabbing the ground, there is more friction on the part that does. This can cause more wear.
But I assume you will mostly be operating the mower on grass, which is soft, so the extra friction will be minimal. You probably won't be driving at the upper end of your mower's speed range, so a rough ride will likely never be a problem.
So in most cases, our main pro outweighs all of the cons.
How Much Does It Cost?
The cost depends on what size tires you have.
If you already have the right drill bit and a valve tool, you'll only need to buy foam. The foam will cost about $45 to fill four small tires and $75 or more for large ones. Add $10 to this if you need a valve tool. You can get a drill bit for a few dollars at most hardware stores.
You won't really save any money by foam-filling your mower tires because it probably won't make them last any longer.
You might save some cash on tire repair if you get your punctures repaired professionally and tend to incur tire damage often. The real advantage here would be saving the time and aggravation of plugging puncture damage yourself.
Could Foam Filled Tires Be Dangerous?
Foam-filled tires present no greater danger than air-filled tires, as long as you follow the proper filling procedure outlined here.
The main thing to pay attention to is the tire's bead. If you don't know what the bead is, it's the part of the tire that contacts the rim and seals the air in. It will be obvious if the bead slips. It will look like the tire is coming off the rim. But if you continue to fill the tire with foam even though the bead is broken, you will end up with an unbalanced tire that may come off the rim while you are mowing.
The main danger while going through the steps outlined here is getting your finger pinched between the tire and rim while moving them around. The cans of foam you're going to use don't really have enough pressure to blow the tire off the rim.
There is a small danger of getting foam in your eyes, but this would be more likely caused by accidentally touching your eyes with foam on your hands. Use common sense, and you'll be alright.
Before You Start...
I've seen tractor supply centers use complicated machines to pump a combination of chemicals into tractor tires to create the foam filling. They do a great job, but you don't need all that equipment to fill your mower tires. What you'll need is pretty simple and basic. Here's the list...
Here's What You'll Need
That's all you need.
Let's talk about the foam. This is critical.
YouTube is full of videos of people filling their mower tires with foam. Not only do most of them do it wrong, but they are using Great Stuff Gaps & Cracks foam. While that's fantastic for filling cracks around the house, it is the wrong kind to fill your tires with. It has low density and expands way too much.
You need a hard, dense foam. I used Great Stuff Pond & Stone's Insulating Sealant (this one here).
Low-density foam gets crumbly very quickly. It can't support the weight of a mower. You would be left with tires full of urethane chunks and powder after a few mows.
How To Foam-fill Your Mower Tires
Make sure you do all four tires. Otherwise, you will have problems with handling and possibly axle damage. Expect to spend about 20 minutes on each tire, so I'd block out two hours of your day to give you enough time to prepare, fill the tires, and some extra time in case you run into any issues.
I can't imagine a mower tire blowing off of its rim under the small amount of pressure it experiences during filling, but it's better to be safe than sorry. I recommend wearing goggles to protect your eyes from flying foam. It's highly unlikely, but the foam can really irritate your eyes. Rubber or nitrite gloves would also be a good idea.
Step 1: Remove The Wheel
Remove a wheel from your mower. Unscrew the valve cap, then slowly remove the valve from the valve stem using your valve removal tool. If you don't have one, I recommend Ares' economy model.
From this point forward, be very careful while moving the wheel around. You don't want to break the bead. You won't need the valve, so you can throw it away.
Replace the valve stem cap tightly, but be careful not to strip it.
Step 2: Drill Holes
Now choose a drill bit that has the same diameter as the straw on your can of foam. Mine was 3/8". Now you're going to do something that you probably never imagined yourself doing...
You're going to drill holes in your tire.
Once you do this, you are committed to foam-filling all four of your mower tires!
You need to drill three holes in each tire. They have to be in the center of the tread, not the sidewall, and they have to be spaced as equally apart as you can get them. The spacing doesn't have to be perfect, but still take some time and mark the spots you intend to drill with a paint marker or chalk. You can eyeball it or use a tape measure, but be sure of your marks before drilling.
Apply steady, firm pressure to the drill. Don't rush it, or the bit will get stuck.
Step 3: Inject The Foam
After you get all three holes drilled, you're ready to fill the tire.
Set the wheel up on a table or cinderblock and lean it back against something, like a post or the side of your house. Rotate it so one of the holes is on the side and pointing at a right angle to the ground. Now push the straw into the hole just far enough so the end of the straw is all the way in the wheel. Pull the trigger on the can and hold it for about five seconds, then let go and wait for five seconds.
Repeat this process of spraying and waiting for about five seconds at a time, all the while watching the other two holes, until you see foam slowly seeping out of one of them.
When you see foam coming from one of the other holes, slowly pull the straw out and push it into the other hole that has not yet leaked any foam. Repeat the filling process until you see foam leaking from the hole that you started filling first.
Next, push the straw into the last hole, even though the tire is filled with foam at this point. Fill through this hole until foam is steadily leaking from both of the other ones.
Congratulations, you just foam-filled your first mower tire! Do the same to the other three.
Step 4: Let It Cure
When you finish a tire, lay it on it's side someplace where it won't be disturbed for 24 hours. The instructions on the can may say that the foam reaches full cure in just a few hours, but that is assuming air circulation. After at least 24 hours have passed, you can remove the dried foam seepage from the holes. You can use a small knife, or just break it off with your fingers and let the next mowing take care of the small stuff that remains.
Step 5: Put The Tires Back On Your Mower
Once you have filled all four of your mower tires with foam, allowed them to cure for at least 24 hours and removed the dried foam from that overflowed from the holes, you can go ahead and put the wheels back on your mower. Start mowing right away if you want to.
What If I Change My Mind?
If for some reason you regret foam-filling your tires, it's too late. The tires have holes in them, and the valve stems are filled with foam.
But there is a way to go back to pneumatic (air filled) tires. The best thing to do is go to a tire center and have them deal with it. You'll need new tires and new valve stems on the rims.
So be sure you want to go foam before you take on this project!
Tried it out? How did it work? Let us know in the comments below!