What you need before you start
You need a new tube that matches your wheel size, two tire levers (plastic or metal), and a pump. The tube size is printed on the side of your tire — common sizes are 700c for road bikes, 26-inch for mountain bikes, and 20-inch for smaller wheels. Buy the tube before you start; trying to patch a tube while your bike is immobilized wastes time.
Tire levers are cheap plastic tools that pry the tire bead (the edge) away from the rim so you can remove the old tube. You can technically use a flathead screwdriver, but levers are designed not to pinch the rim or puncture the new tube. Keep them in your repair kit.
A hand pump or floor pump gets air back into the tire once the new tube is seated. A floor pump is faster and easier on your hands, but a hand pump works if that is what you have.
Key Takeaways
- Remove the wheel from the bike, then use tire levers to pry one side of the tire away from the rim and pull out the old tube.
- Check inside the tire for thorns, glass, or sharp objects that caused the puncture, or you will flatten the new tube when ready.
- Insert the new tube by first inflating it slightly so it holds its shape, then seating the valve stem through the rim hole and tucking the tube under the tire bead all the way around.
- Pry the tire bead back onto the rim using your hands first, then tire levers only if needed, working from the valve stem outward.
- Inflate the tire fully and check that the tire bead sits evenly on both sides of the rim before riding.
Remove the wheel and old tube
Flip the bike upside down so it rests on the handlebars and seat, or use a bike stand. For the front wheel, open the quick-release lever (or unscrew the axle nuts if your bike has them) and lift the wheel out of the fork. For the rear wheel, shift to the smallest cog, open the quick-release, pull the derailleur back, and lift the wheel up and out of the chain.
Once the wheel is off, locate the valve stem — the metal or plastic post sticking out of the rim. Unscrew the valve cap and set it somewhere you will not lose it. If your tube has a removable valve core (a small metal piece inside the stem), unscrew that too; if not, skip this step.
Insert a tire lever under the tire bead about 6 inches away from the valve stem. Pry the bead away from the rim and hook the lever to a spoke. Insert a second lever about 12 inches away and repeat. Once you have two levers hooked, the bead should be loose enough to slide your fingers under and pry the rest of the way around the rim by hand.
Pull the old tube out completely. It does not matter if it is punctured — you are throwing it away. Set the tire aside; you will need it in a moment.
Inspect the tire for what caused the puncture
Run your fingers slowly along the inside of the tire, feeling for thorns, glass shards, or sharp wire. This is the most important step. If you skip it and install a new tube without removing the object, the new tube will puncture in the same spot within a few miles.
Pay special attention to the sidewalls and the area around the bead. Thorns often lodge at an angle and are straightforward to miss. If you find something, pull it straight out. If the tire has a visible cut or tear in the rubber, the tire itself may need to be replaced — a new tube alone will not hold air if the tire is damaged.
Once you are confident the tire is clean, visually inspect the rim tape (the strip of rubber or plastic covering the spoke holes). If it is torn or missing, sharp spoke ends can puncture the new tube. Rim tape is cheap and takes two minutes to replace; do it now if needed.
Install the new tube
Inflate the new tube slightly — just enough so it holds its shape and is not completely flat. This makes it easier to position without twisting or pinching it. Do not inflate it fully yet.
Insert the valve stem through the hole in the rim first. Make sure it goes straight through and sits flush against the rim. Then, working from the valve stem outward in both directions, tuck the tube under the tire bead all the way around the wheel. Go slowly and make sure the tube is not twisted or folded under itself.
Once the tube is fully tucked, the tire bead should still be sitting on top of the rim on one side. You now need to pry that bead back down onto the rim to trap the tube inside. Start at the valve stem and work your way around, using your hands to roll the bead down. Most of the way around, your hands are enough.
When you get to the last 12 inches, the bead will be tight. Use a tire lever to pry it down, but be careful not to pinch the tube. Insert the lever under the bead, pry gently, and move it a few inches at a time. Work from both sides toward the last tight spot. Once the bead is fully seated on the rim, the tube is trapped inside.
Inflate and check the seal
Inflate the tire to about half pressure using your pump. Stop and visually inspect the tire bead on both sides of the rim. The bead should sit in a consistent groove all the way around, with no bulges or dips. If you see the tube peeking out from under the bead anywhere, deflate, reseat that section, and try again.
Once the bead looks even, inflate to the pressure printed on the tire sidewall. This is usually between 40 and 100 psi depending on the tire type. Check the bead one more time — it should not move or shift as you add air.
Screw the valve cap back on. If your tube had a removable valve core, screw that back in first, then the cap.
Reinstall the wheel on the bike
For the front wheel, lift it into the fork and make sure the axle sits fully in both dropouts (the slots at the end of the fork). Close the quick-release lever or tighten the axle nuts. Spin the wheel to confirm it does not rub the brake pads or frame.
For the rear wheel, pull the derailleur back with your right hand, lift the wheel into the chain, and lower it into the dropouts. Make sure the axle is fully seated on both sides. Close the quick-release or tighten the nuts. Spin the wheel and shift through the gears to confirm the chain tracks smoothly.
Flip the bike right-side up and squeeze the tire with your hand. It should feel firm but have a small amount of give. If it feels mushy, add air. If it feels rock-hard, you may have overinflated — let a tiny bit out.
What to do if the new tube will not hold air
If the tire loses pressure within an hour of installation, the tube is either pinched between the tire and rim, or there is still a sharp object inside the tire. Deflate completely and remove the wheel again. Pry the bead back off and inspect the tube for small holes or punctures. If you find one, the tube is defective — replace it with another new one.
If the tube looks intact, remove it and inspect the tire interior again, this time more carefully. Run your fingers along every inch of the inside surface. Check the rim tape again. Once you are certain the tire is clean, reinstall the tube and inflate slowly, watching for any hissing sound that would indicate a leak.
If the tube still fails, the tire itself may have a hole or tear. Inspect the outside of the tire under bright light. If you find damage, the tire needs to be replaced, not just the tube.
Frequently Asked Questions
Can I patch the old tube instead of replacing it?
You can, but only if the puncture is small and you have a patch kit. Patches work best on slow leaks caused by small holes. If the tube is torn, has a large puncture, or the valve is damaged, patching will not hold. For a roadside repair, a patch buys you time to get home; for a permanent fix, a new tube is more reliable.
What if I do not know my wheel size?
The size is printed on the tire sidewall in large numbers — look for "700c", "26 inch", "20 inch", or similar. If the sidewall is worn and unreadable, measure the wheel diameter with a ruler or tape measure. Bring that measurement to a bike shop and they will tell you the correct tube size.
How tight should the tire be when I inflate it?
Inflate to the pressure range printed on the tire sidewall. This is usually 40 to 100 psi depending on tire type and width. Use a pump with a pressure gauge so you can see the exact number. If you do not have a gauge, squeeze the tire with your thumb — it should feel firm with just a small amount of give.
Why did my tube puncture in the first place?
Most punctures come from thorns, glass, or sharp wire embedded in the tire. Some come from pinch flats, which happen when the tire pressure is too low and the tube gets squeezed between the tire and rim. Check the pressure regularly and keep your tires inflated to the recommended range to prevent this.
Do I need to replace the tire if it has a puncture?
Not necessarily. The tire is just rubber; the tube is what holds the air. If the tire has no visible cuts or tears and the puncture came from a small object like a thorn, the tire is fine. If the tire has a gash, split, or large hole, it needs to be replaced because a new tube will not seal the damage.