Tubeless or tube, and what it actually changes
Short answer: a tube makes your number go up. If you switched to tubeless and kept pumping to the same pressure, you have been riding hard ever since.
Here is the size of it, and the part we are not sure about.
A tube asks for more air, not less
The common belief is that going tubeless is what lets you run low pressure. It is the other way round: the tube is what makes you run high. Take the tube out and nothing else changes, and the same tire on the same rider wants less air, not more.
Front / rear psi at 190 lb all in, 40 mm, mixed gravel
| Setup | Effect | Front / rear |
|---|---|---|
| Tubeless | 0% | 37 / 40 |
| TPU tube | +4% | 39 / 41 |
| Latex tube | +5% | 39 / 42 |
| Butyl tube | +9% | 41 / 43 |
At that setup a butyl tube costs you 3 psi on the rear over the same tire run tubeless. Latex and TPU sit between the two, closer to tubeless than to butyl.
The tube is carrying part of the load
A tire holds you up two ways: the air inside it, and the casing itself acting as a spring. Add a tube and you add a second layer that resists being deformed — but it resists in a way that fights the casing rather than helping it, and it loses energy as heat every time the tire flexes. The practical result is that the air has to do more of the work, so it needs more of it.
That is also why a tube feels dead. You are not imagining it. The energy going into warming the tube is energy that is not coming back out at the other side of the bump.
We are not certain about the size of it
The 9% above is our figure. We could not find agreement on it anywhere — not on how big the effect is, and not even reliably on which direction it runs. Some sources put a tube at a lower pressure than tubeless, which is the opposite of what we concluded.
So we picked the firmer end on purpose. Being slightly over on a tube is the safer way to be wrong: too much air on a tube is a harsher ride, and too little is a pinch flat against the rim. One of those ends your afternoon.
If you ride tubes and the number comes out harsher than you like, take it down and rate the ride. The app will move it toward you, and on your bike your hands are better evidence than our multiplier is.
Now move both and watch where you land
The two tables above each hold one thing still. Real bikes do not: you switched to tubeless and put a tougher tire on for the winter, and the two changes pull in opposite directions. Here is every combination, with the same rider on the same ground.
A butyl tube in a standard casing asks for 3 psi more on the rear than the same tire run tubeless.
The spread from end to end is wider than either lever alone, which is the whole point. A supple tire with a butyl tube and a reinforced one run tubeless are the same tire size on the same bike, and they are not the same number.
Casing pulls the same lever
The same logic runs through the casing choice, and it is worth knowing because it is the adjustment riders most often forget they made. A reinforced or puncture-protected casing is stiffer, so it carries more of the load itself, so it wants less air. A supple high-thread-count casing wants a little more.
The same setup, changing only the casing
| Casing | Effect | Front / rear |
|---|---|---|
| Supple | +2.5% | 38 / 41 |
| Standard | 0% | 37 / 40 |
| Reinforced | -5% | 35 / 38 |
If you switched to a tougher tire for a rough season and kept pumping to your old number, you have been running hard without deciding to.
What this page is not saying
Nothing here is an argument for going tubeless. Tubeless is fussier to set up, it can fail in ways a tube cannot, and a tube in a saddle bag is still the fix when it does. This is only about what the choice does to the number you pump to.
Tell the calculator which one you are actually running and it will account for it. That is the whole point of asking. If you ride gravel, the table on the gravel page is the tubeless one — add a few psi to every figure on it.