MTB Tire Pressure Calculator (Quick & Easy)
For mountain biking, tire pressure is one of the most important factors for bike setup, but also one of the most confusing. It doesn’t help that there’re two common units of measurement – bar and PSI (pounds per inch) – and countless variables to factor in. That’s why finding your optimal pressures seems incredibly difficult. But is it really?
Let’s reduce the guesswork and number crunching down to one single variable:
Rider weight (including gear and backpacks) is the single most important factor here to calculate a decent baseline value for front and rear tire pressures. This method gets pretty close to optimal values for you. Try it out with the calculator below:
Mountain Bike Tire Pressure Calculator
(There are minimum and maximum values to ensure there is actually enough and not too much air in the tires.)
An accurate pressure gauge is critical to reliable, consistent tire pressures every time. I personally use the Topeak Smartgauge D2 before every ride. It works great for Presta and Shrader valves and is just as good as the newer, more expensive D2X version.
How to use this calculator
This tire pressure calculator operates by the 80/20 rule and eliminates all input variables but one: the actual rider weight including gear, protection, backpack, hydration pack etc. This is also a fairly constant variable that doesn’t change day-to-day.
The calculator is designed to be easily accessible for any mountain biker. It’s optimized for All-Mountain riding (Enduro & Trail) where uphill and downhill performance are equally important. For purely Cross Country (where rolling resistance is key), E-MTBs (heavier bikes) or Downhill MTB (where stability is key), you may go up 2-5 PSI from the results above.
In any case, don’t expect THE one and only true perfect number to appear out of a calculator. There are so many other variables that are very individual and even vary even with the same rider on the same day. So I’m not even going to pretend there’s one perfect pressure for anyone. Rather calculate a reasonable optimal pressure as a baseline.
Why are front and rear tire PSI different?
The front and rear tires have different jobs to do, which are even more of a balancing act on a mountain bike. Both need to dig into the ground for grip. Additionally, the front is used for cornering and braking so it needs to be stable but also conform to the ground for grip on uneven surfaces. Most of the body weight is over the rear tire, which has to translate the pedaling power to the ground. Rolling resistance and acceleration are primary concerns.
As you can see, it’s always a balancing act between grip and rolling speed. More is not necessarily better like on a road bike, which has to roll fast but not grip through tight corners. Low pressures have their downsides too as they’re the reason for bottoming out, burping a tire or having sluggish, inefficient handling.
For me personally, at 75kg I settled on 23psi front and 27psi rear for Enduro using tubeless tires and 24psi front and 29psi rear on the Downhill bike with tubes and DH casings. I like to keep those constant even when conditions change for an extremely reliable feel. 1 or 2 PSI off is instantly noticeable (sluggish and slow or harsh and skaty).
Tip: Bookmark this page on your phone for quick and easy calculations out on the trail.
Find your optimal PSI
Disclaimer: Don’t expect to find the perfect pressure – not quickly at least. Finding your optimum is a constant process and a calculator will never be able to give you a definitive result, but a pretty good starting point. Rider weight as an input variable delivers a good estimate. And it’s relatively constant over time, which helps in finding baseline pressures you can use 90% of the time and get accustomed to. Extreme conditions like snow, deep mud and hard asphalt require adjustments.
There are many more variables and factors affecting tire pressures:
- Trail Surface and conditions (mud, gravel, hardpack, rocks, loam)
- Tubeless or tube (tubeless can go lower without a higher risk of punctures, but do you even want to?) I don’t see a reason to go with lower pressures because of greatly reduced rolling speed and increased output pedaling
- Tire width (i.e. tire volume)
- Rider weight (additional gear, accessories)
- Tire profile (tread pattern and grip)
- Tire sidewall & puncture protection (casing)
- Tire rubber compound
- Trail navigation (more uphill or downhill? some release air before a downhill)
- Speed and skill level (the faster you go, the harder you’ll hit stuff and the more pressure you’ll need to not break the rims or get punctures)
- Riding style (smooth operator or bulldog)
- Altitude and air density (obviously changing with climbs and descents …)
Some never change, some do from day to day, and some do while riding. It doesn’t make sense to chase any of them but rather I would argue us non-professionals should seek to maximize your own rider comfort and trust in your tires. You do that by picking a baseline for a bike and go only slightly up or down from there.
To play around you can bookmark this calculator or the tire pressure chart I created here for quick reference.
Why tire pressures matter (so much)
Can you guess what cornering harder, having more grip, trusting your tires, pedaling faster, minimizing vobrations, preventing flat tires and feeling reliably comfortable on your bike all have in common? All of those can be improved with a free upgrade: knowing how much air is in your tires.
I found that if you always stick with the same pressures, the grip level and handling become very predictable, even in varying conditions. It’s the idea of reducing the number of variables by keeping constant what you can. I even wrote an entire article explaining why the correct MTB tire pressures are so important (including more actionable tips).
For most amateur riders (myself included) we don’t need to get every millisecond and milligram out of our equipment. But we want to maximize fun and enjoyment while out on a group ride. By not thinking about the equipment and setup all the time.
Like you won’t adjust handlebar roll or suspension pressure multiple times a day before every new trail, the same can be said about tire pressures. Set once and forget – but constantly check.
How to accurately measure tire pressure
Have you ever wondered why your bike seems to stick to the ground like velcro on day and skipps all over the place the next? My questions would be what the PSI on both days were. It’s a metric that needs to be measured regularly as air escapes the tires over time. Air particles are just small enough to slip through the rubber.
So how do you measure how much air is in your tire? Spoiler: Not your thumbs. No matter how long you’ve been pushing them into your tire and pretending that it’s telling you something. All your thumbs are telling you is that there’s air in there, not how much air is in there. Accurate numbers are truly important here!
The best move is to get yourself some sort of pressure gauge. I know tire pumps come with built-in gauges and those are a good starting point. But tire pump gauges (often analog) are just not accurate enough for you to measure in a reliable fashion.
My Joe Blow pump has a gauge, but I still got a separate handheld gauge. The pressure gauge I always keep in my toolbag is the Topeak D2 SmartGauge (picture at the top). It easily slips onto any valve without screwing or swapping adapters.
High-volume tires VS low-volume tires
Let’s talk about high-volume tires versus low-volume tires and why is it they require completely different air pressures. Similar to basketballs and handballs. A high volume wide tire (like plus size or fat bike tires) is a basketball and a low-volume tire ball is a handball.
High-volume Fat Bike tires work very differently and depend equally as much on the trail or road surface. The calculator is not designed for huge fat bike tires or tiny road bike tires for that matter.