Avoid Flat Tires On Your Mountain Bike: 9 Helpful Tips
What modern mountain bike tires are capable of when they are working as intended is incredible. Even greater is the disappointment when they stop working – for one reason or another. One very common reason for tire malfunction is the treaded puncture.
Flat tires always happen at the worst of times (they’re never welcome), and can even get quite dangerous if air leaks in a quick manner leaving you hanging with no traction. Even worse is when there is no way to repair or swap the tire. Then the ride is over and the walk home is long.
But that doesn’t have to be. There are ways to minimize the risk of flatting your tire. And before we can discuss preventing tire flats, let’s quickly go over what factors can result in flat tires so we can eliminate them.
Why do flats even happen in mountain biking?
Flat bike tires can happen for four main reasons:
- Pinch flat (or snakebites): When the tire and tube are pinched between the ground and the rim.
- Puncture: When sharp or pointy objects puncture through the tire tread or sidewall and the tube.
- Technical malfunction: When vavle is leaking, the rubber of the tire or tube gets brittle and starts tearing or the rim is damaged.
- Tire burping: On tubeless tires only, burping happens when the tire bead is pulled off from the rim momentarily, releasing air.
One was a snakebite, the other a puncture by a pointy rock.
The pinch flat and puncture flat are by far the most common ones in mountain biking. And they are easily avoided with the correct preparation.
1: Don’t run tire pressures too low
Low tire pressures are by far the most common reason for flat tires in MTB. It’s the cause of pinch flats, punctures and burped tires. A tire can absorb so much of the initial impacts before it reaches the rest of the bike, but with less pressure, it can do so less.
In MTB you want lower pressures to allow the tire to conform to the ground and really dig in to generate traction where the terrain offers little. But running it too low for your weight and riding style has two issues:
- The sidewalls get pushed out, making them prone to sidewall slashes.
- Less force is needed for the rim to touch the tire casing and pinch the tube.
- And the tire bead sits looser on the rim so it can be pulled off my aggressive cornering.
If low tire pressures result in flat tires, why don’t you just pump up your tires to the absolute max?
2: Don’t run tire pressures too high either
It’s not recommended for any MTB tire to inflate to the highest possible pressure it can handle. The reason is that a tire needs to conform to the ground in order to generate traction and absorb minor bumps. High tire pressures improve rolling resistance but to the detriment of handling.
More importantly in the context of flat prevention, it takes away the ability of the tire to conform over terrain and sharp edges. This allows pointy terrain features to penetrate the tire with more force.
We don’t need to go into the details here, but if you do, I wrote an entire article on why tire pressure is critical for mountain biking. It also shows you how to find the best tire pressure for you. Instead, I’ll leave you with this simple message:
There is in fact a definitive psi number printed directly onto the sidewall of any tire. On my Maxxis Minions, it’s a whopping 50 psi. But please do not mistake those numbers for recommended values! Those are not instructions but legal safety claims.
Bonus Tip: Check tire pressures before every ride
Bicycle tires lose air over time because air molecules are tiny enough to get pushed through solid rubber. It’s the same reason why your birthday balloons are going to be just as deflated the next day as you after a proper party. So when bike tires can’t keep the air in them indefinitely, checking and setting your pressures for every ride is highly recommended for reliable handling.
Bike pumps with analog pressure gauges are very common these days. I personally use the popular Joe Blow bike pump from Topeak to pump up my tires before every single ride.
That’s enough for most recreational riders. I personally really want to get the correct pressure down exact PSI values. So additionally, I pump them up a little too much and use the digital Topeak D2 SmartGauge to let out air until I see the numbers I want to see.
If you’re wondering, here’s how to accurately measure tire pressures on a bike. And no, it’s not using your fingers.
3: Use appropriate tire casings for the type of riding
The best tire pressure, tuned to the exact PSI (or Bar) value, isn’t going to save you if you use the wrong tire casings for the job, to begin with. In particular, a tire casing that offers not enough protection for the type of riding and terrain at hand. Protective rubber matters, people.
The basics of protection in MTB casings are as follows: There is either none, sidewall protection only or sidewall protection combined with a bead-to-bead layer. For any more info, I explain MTB tire casings in detail here.
The variation in tire casings may be confusing, but there is good reason for the range of options. Tire protection adds weight, which sometimes creates a new problem by solving another one. Some MTB disciplines like XC and Trail are more focused on efficiency and weight-saving, others like Enduro and Downhill take every bit of resistance they can get.
If you ride aggressively with heavy hits, save yourself time, money, and your patience by going for a heavy-duty tire casing at least in the rear of your bike. Due to the higher weight and harsher impacts the rear tire has to endure, punctures are more frequent there.
4: Line choice on the trail
Here’s an innovative tip to not get your tires slashed by sharp edges: Don’t ride over them. Granted, that was only marginally helpful.
But on a serious note, line choice out on the trail is a legit way to avoid punctures. You may either pick a line, that you know your bike and tires can handle if you encounter an exceptionally rough bit of singletrack.
Or you may alter your line depending on the speed you are going to not hit sharp edges harder than you need to. Pumping and jumping can help in making the bike lighter over pointy objects and dig into the ground when it’s softer.
This is of course a matter of skill and experience on various terrain. And it can be learned as it improves with repetition and time on the bike. The better you know a trail, the easier it is to look ahead and recognize trail features in advance. It’s also a function of how well you know your bike and the components like rims and tires on it.
A hardtail is obviously more puncture-prone than a full-suspension bike due to the ability to absorb impacts through suspension travel and needs to be ridden at different speeds or on different lines than a fully.
5: Use correct tire width for the rim width
A bulging tire, that gets easily punctured through the sidewall, can not only happen with too low pressure but also with a too narrow rim or too wide tire. The alignment of rim width and tire width is in fact crucial to the overall tire profile.
Only the optimal rim width, which a tire is designed for, gives it the shape it needs to work properly. Stans NoTubes have a very illustrative comparison of what happens if you run the same size tire on different rim widths. Left is wrong, right is right
You want to have the recommended rim and tire widths go together for the best-performing wheel. To make things simple, I compiled the recommended tire widths for a given rim width here.
6: Replace old, brittle tires
It’s no secret that rubber in any form will get brittle over time. Even if the tire tread is still good, your old tire might be showing signs of giving up. On my trail bike, I ran a tire for close to 4 years. It had a tall tread and for the rear tire, the ground down lugs were still enough for a rear tire.
Even with riding on loamy, not rocky terrain, the tire showed its age, very noticeably on the tread that got abused over the years. So even if the tire tread is still good, its ability to keep air will fade with time.
Old tires are one reason for the slowly leaking flat tires or overnight flats. The same can happen with rubber tubes and valve cores.
7: Replace brittle tubes and old valves
If you feel like your tires are losing air too fast (overnight) it could be down to another issue: The valve stem and tube connection for tube tires or the valve stem and rim interface on tubeless tires.
Tube tire: A very common area where tubes get damaged over time is the seal between the tube and valve stem. It’s the frailest part of the entire tube. Like any seam, the seam between the tube and the valve stem is fragile and inclined to start leaking air from the tiniest hole. Again, the older it gets the more prone it is to getting tears and holes by itself.
Tubeless: Just give it a shake and put your ear close to the valve. If anything is loose, you could actually hear more air come out. In the case of air exiting from the valve area, check by tightening that lock nut from where you’re losing your air from. This may include checking on the valve core too. I had a very sudden change in how well my front wheel could hold air. It wasn’t the nut at the interface of the valve to the rim, it was that the valve core itself was loose.
8: Switch to tubeless tires with tire sealant
One top hack to eliminate all pinch flats forever is to actually not use tubes anymore. And it’s actually easy to do, especially if you already know how to change a tire yourself.
In fact, you can put a tubeless tire on a tubeless compatible rim with an air-tight rim tape and valve, and inflate it. There is no need for any sealant to make the system air-tight. Rim and tires are designed to do that by themselves. That’s why snakebite pinch flats with tubes sometimes can be ridden for quite some time after the fact.
Still, I wouldn’t recommend keeping tire sealant out of the equation entirely. You still can get punctures and the sealant is one of the three main benefits of tubeless tires as it manages to keep air in your tires with minimal pressure loss. The other benefits are of course lower tire pressures and lower weight.
Tubeless tire sealant is optional but highly recommended to automatically seal small punctures.
9: Use tire inserts with tubeless tires for rim protection
MTB tire inserts are similar to tire mousse used in motocross: hard foam is installed in tubeless tires only. They allow for lower pressures and more traction by reducing air volume and protecting the rim and tire in case of a pinch.
They do add extra weight (turns out dense foam is heavier than air), which may be a consideration depending on the type of riding you do. For full-on downhill riding in chunky terrain, the benefits outweigh the costs in cash and additional weight. For long enduro rides with technical descents, where mechanical problems can’t so easily be fixed and spares are scarce, one insert in the rear tire may be an option. For weight-critical riding like trail and cross country, these are not really worth thinking about.
Popular tire insert brands are Cushcore, Huck Norris, Schwalbe Procore, Marshguard FCK Flats, Nukeproof, Tannus, Rimpact, Vittoria, and Panzer.
And that’s it. Those are the basics to prevent flat tires on your next MTB ride. Keep the pressure on and keep riding on! Cheers.
