Tire pressure is important for your car, but it’s arguably just as important for your mountain bike (even more than your street bike).
Tire pressure directly relates to how shock-absorptive your mountain bike is going to be, and if you’ve been on any trail recently, you know exactly what the shock can do when you hit it the wrong way. It isn’t good.
Mountain bike tire pressure is touchy, so you’ll have to check it every single time before you leave the house.
It’s also good to have a pump on you and a tire pressure gauge at the same time. This is what you need to know.
- 1 Why is Tire Pressure Important?
- 2 Optimal Tire Pressure for Mountain Bikes
- 3 Dangers of Too Low Tire Pressure
- 4 Dangers of Too High Tire Pressure
- 5 Your Sidewalls Are the Most At-Risk Portion of Your Tires
- 6 Carry a Spare Gauge and Pump
- 7 Just Like Goldilocks, it Has to be Just Right
Why is Tire Pressure Important?
Tire pressure is directly related to safety. This is true for any tire, whether it’s on a bicycle or a car.
Tire pressure is usually specified by a manufacturer, so tire pressure values can change. With bicycles, they can often change depending on what the tires are used for.
Winter tires for a hybrid bike might have different psi ratings than winter tires for a mountain bike.
Standard, non-winterized tires may also have an entirely different recommended psi value as well.
Without pressure in the tires, you can blow them out entirely, and there’s no coming back from that.
The tires end up going in the garbage. We explain more about the whys behind that later on in the guide, but suffice it to say that tire pressure is incredibly important.
As a matter of fact, you should have a miniature bike pump with you (if you have the room) in your backpack, as well as a tire pressure gauge that is specifically designed for bicycle tires. Test often, and inflate as needed.
Optimal Tire Pressure for Mountain Bikes
Get this—narrow tires actually need more pressure than big, thick, bulky mountain bike tires. So a street racing bicycle that features road tires needs around 80 psi up to 130 psi to be effective.
It’s why road tires have a higher chance of blowing out, and why you really shouldn’t use street bikes on rough terrain. It’s not just some hyperbole that you remember your dad telling you when you were a kid.
Now, when you get into hybrids, you end up with an acceptable range of around 40 psi to 70 psi.
That’s a huge dip compared to road tires, but you might be surprised to find that all-mountain bikes have an even lower tire pressure. You only need 25 psi up to 35 psi for your mountain bike tires.
This is because the rugged construction of the tires and the way they’re designed handle a lot of the shock through thicker rubber.
With that range, we can assume that 30 psi will be the best bet for mountain bike tires.
It’s important to check the tire manufacturer’s recommendations to be 100% sure, because there are some mountain bike tires that have slightly different ranges, such as 30 psi to 40 psi.
Even if you have handling and care information from the bicycle manufacturer, check the tires anyway. They may be third-party tires that have different information than what the instructional booklet says.
This isn’t common, but it happens, and it’s better to be thorough in this situation so you don’t blow through your tires.
Dangers of Too Low Tire Pressure
If the pressure is too low, it doesn’t take long to completely ruin your tires. We’re talking about blowouts, thin thin tires, and a heightened risk for severe injuries from serious accidents.
Increase in Friction
When the sidewalls of the tire don’t have enough air, they take on the force of shock as you ride.
Not in the way that tires are supposed to, mind you.
The sidewalls flex more and more until friction is produced, and that friction heats the sidewalls up past any point that they should be.
Rubber begins to separate from the carcass, and this can lead to numerous problems.
Higher Chance of Blowouts
When your tire is low on pressure, it feels loose.
That’s the best way to describe it. When it feels loose, your steel tire rim will begin to jostle it around since it’s not firm and secure where it’s supposed to be.
The tire moves around until the steel rim separates from it entirely, the steel rim hits the ground to absorb friction, and as it begins to spin instead of the tire, the tire gets caught up and shredded extremely fast.
Loss of Control
Without proper friction on the ground or asphalt, wherever you’re riding your mountain bike at the time, the tire will move around the rim.
That’s a force that you can’t control with steering and dexterity.
You’ll notice an immediate loss of control, and at high speeds, this could cause a crash as the warped tire begins to fold underneath the weight of the steady steel frame.
Dangers of Too High Tire Pressure
Believe it or not, you really can have too much of a good thing, even in the case of tire pressure.
The common misconception is “Well, at least it isn’t low,” but you can run into similar issues with over-inflated tires including blowouts, easier hydroplaning, and more.
Easier to Hydroplane
When tires are overinflated and your traction is lessened, water becomes a much bigger issue than it already is.
Mountain bike tires are supposed to have deep treads to help you find traction even in adverse weather conditions, but without those deep pockets and divots in the treads, traction can’t be achieved.
Traction is what helps prevent friction from becoming a problem for your tires. Without traction, you don’t have any stability or grippiness on the ground, and you just slide all over the place.
If your tire pressure is too high, it can force portions of the tread to wear down faster, leaving you with a smooth tire that doesn’t work well for mountain biking.
Higher Chance of Blowouts
When you go off a small jump and feel the resistance from landing on the edge of a rock or section of a boulder, your tire withstands a lot of that impact.
But the treads alone can’t handle all that shock, and when your tire is overinflated but receives that shock anyway, there’s less room for your tire to bounce. It ends up popping, or blowing out.
Less Powerful on Mountain Terrain
While you would think that higher tire pressure would mean more power, it doesn’t.
When the pressure increases, spots between the treads of the tire overinflate, causing that smooth area to bulge out and contest the grippy surface of the rest of your tire.
Now you have portions of the tire that aren’t making contact with the ground properly, so you’re losing that valuable bit of traction.
Your Sidewalls Are the Most At-Risk Portion of Your Tires
Your sidewalls withstand a lot of impact on a regular basis, but when you have the wrong psi, it’s a recipe for disaster.
The sidewalls are often overlooked during mountain bike maintenance.
Cyclists instead focus on the depth of their treads to signify whether or not a specific set of tires is still good, but that’s not all they should be checking.
Sidewalls will be different for different brands.
Some will be ultra-thick, while others are thinner to provide better bounce during high-pressure situations (questionable, unpredictable terrain to be more precise).
Inspect your tires, but especially your sidewalls, for the following issues:
- Thinner than normal patches
- Visibly lighter or less dark spots
- Cracked or split rubber
- Flat or worn spots
These can all be indicative of an issue with the sidewalls, but you should also take a look at the treads and tires as a whole to spot these issues as well.
Carry a Spare Gauge and Pump
Pack a small gauge and pump in your backpack when you head out with your mountain bike, even if you’re just going down the street to the convenience store. It doesn’t matter.
You want to be ready and able to check your tires.
The good thing is that after a while, you’ll only really know what it’s like to ride on a perfect psi rating, so you’ll be able to detect when something’s off with the tire pressure just from the way it feels during your ride.
Get in this habit and your tires will last you longer, meaning less expenses in the future, and less headaches trying to fit them onto the rims as well.
Just Like Goldilocks, it Has to be Just Right
Your tire pressure has to be perfect every time that you leave to hit the trails . Anything less, and you’re putting yourself at risk, and your mountain bike maintenance will become a chore.
Keep the pressure just right, otherwise you’re going to go through more tires than need be.