What you need before you start

Changing a flat tire requires three things: a tire lever (also called a tire iron), a replacement inner tube or a patch kit, and a bicycle pump. Tire levers are flat metal or plastic tools that pry the tire bead away from the rim. You need at least two, though three makes the job easier. A replacement tube costs between $8 and $20 depending on your wheel size; a patch kit costs $3 to $8 and lets you repair the old tube instead of replacing it. A hand pump or floor pump inflates the new tube back to pressure.

Before you ride, know your wheel size. It is printed on the tire sidewall — common sizes are 26 inches, 27.5 inches, 700c, or 20 inches. Buy a replacement tube that matches your size and valve type. Most modern bikes use Schrader valves (look like car tire valves) or Presta valves (thinner, with a small locking nut at the top). Mismatched tubes will not fit.

Keep a tire lever, a spare tube, and a pump in a small bag under your seat or in a backpack. You do not need to carry them on every ride, but having them means you can fix a flat miles from home instead of walking your bike back.

Key Takeaways

  • Remove the wheel by opening the quick-release lever or unscrewing the axle nuts, then use tire levers to pry one side of the tire off the rim.
  • Pull out the old tube, inspect the tire interior for thorns or glass, and remove any debris you find before installing the new one.
  • Seat the new tube inside the tire, starting at the valve, then use your hands to work the tire bead back onto the rim before using levers.
  • Inflate the tire to the pressure printed on the sidewall, checking that the bead is seated evenly on both sides as you pump.
  • Reinstall the wheel, making sure the brake pads are not rubbing and the quick-release or axle is tight before riding.

Remove the wheel from the frame

Flip your bike upside down so it rests on the handlebars and seat, or use a bike stand if you have one. This keeps the wheel accessible and your hands free. For the front wheel, open the quick-release lever on the left side of the hub (the center of the wheel) by flipping it outward, then unscrew the bolt on the right side by hand until the wheel lifts free. If your bike has axle nuts instead of a quick-release, use a wrench to unscrew both nuts, one on each side of the hub.

For the rear wheel, shift the chain to the smallest cog first, then open the quick-release or unscrew the axle nuts the same way. Pull the derailleur (the mechanism that moves the chain) backward and lift the wheel out of the chain. Set the wheel on the ground in front of you.

Remove the tire and old tube

Let out any remaining air by pressing the valve. Insert a tire lever under the tire bead (the edge of the tire that sits on the rim) about six inches away from the valve, then pry the bead over the rim edge. Slide the lever around the rim to free one side of the tire completely, or use a second lever and work your way around in sections. The tire does not need to come all the way off — you only need one side loose.

Reach inside and pull out the old tube. Inspect the inside of the tire carefully, running your fingers along the interior surface to feel for thorns, glass shards, or sharp objects. Even a tiny piece of debris will puncture the new tube. If you find something, remove it. Look at the tire for cuts or damage; if the sidewall is torn or the tread is severely worn, the tire itself needs replacing, not just the tube.

Install the new tube

Inflate the new tube slightly — just enough so it holds its shape and does not fold on itself. This prevents twisting and pinching when you install it. Insert the valve through the rim hole first, then work the tube around the inside of the tire, making sure it sits evenly and does not bunch up anywhere.

Starting opposite the valve, use your hands to roll the tire bead back onto the rim. Work your way around in both directions toward the valve, pushing the bead down and inward as you go. When you reach the valve, the last section of bead will be tight. Push the valve up into the tire to create slack, then roll the final bead section onto the rim. Do not use tire levers for this step — your hands are gentler and less likely to pinch the new tube.

Inflate and check the seal

Attach your pump to the valve. For a Schrader valve, push the pump head straight on. For a Presta valve, unscrew the small locking nut at the top first, then push the pump head on. Inflate slowly and watch the tire bead as you pump. The bead should seat evenly on both sides of the rim, creating a visible line where the tire meets the metal. If one side bulges outward or inward, stop, deflate, and reseat that section by hand before continuing.

Inflate to the pressure printed on the tire sidewall. This is usually a range — for example, "80–100 psi" — so aim for the middle or slightly higher. Do not over-inflate; the tire will bulge and may burst. Once the tire reaches pressure, remove the pump and check that the bead is still seated evenly all the way around. If it looks right, you are done inflating.

Reinstall the wheel

For the front wheel, lift it into the fork (the two arms that hold the wheel), making sure the axle sits fully in both dropouts (the slots at the end of the fork arms). Screw the right-side bolt by hand until snug, then flip the quick-release lever closed. It should require firm pressure — if it closes too easily, open it and tighten the bolt more. If it is too tight to close, loosen the bolt slightly.

For the rear wheel, pull the derailleur back and lift the chain onto the smallest cog, then guide the wheel into the frame. Make sure the axle sits fully in both dropouts. Screw the right-side bolt and close the quick-release the same way as the front. Spin the wheel to make sure it does not rub on the brake pads. If it does, the wheel is not centered — remove it and reseat the axle.

Flip the bike upright and spin both wheels to confirm they turn freely. Squeeze the tire with your hand to double-check the pressure feels right. Take a short test ride in a safe area before heading out on the road.

Patching a tube instead of replacing it

If you do not have a replacement tube, you can patch the old one. Locate the hole by inflating the tube and listening for a hiss, or submerge it in water and look for bubbles. Dry the tube completely. Use the sandpaper from your patch kit to roughen the area around the hole, then explore the adhesive (if your kit requires it) and wait the time specified on the package — usually 30 seconds to two minutes.

Press the patch firmly onto the hole, holding it for the time listed on the kit, usually one to three minutes. Peel away the foil backing slowly. Let the patch cure for at least five minutes before reinstalling the tube. Patching works well for small punctures but is slower than swapping tubes. If you get multiple flats, carrying a spare tube is faster and more reliable than patching roadside.

Frequently Asked Questions

What causes a bicycle flat tire?

Punctures from thorns, glass, or sharp objects are the most common cause. Pinch flats happen when you hit a pothole or curb hard enough to squeeze the tube between the tire and rim, creating two small holes. Slow leaks come from valve damage, a cracked tube, or a worn tire. Check the tire interior and the valve when you remove the old tube to understand what caused the flat.

Can I ride on a flat tire to get home?

Riding on a flat damages the tire sidewall and the rim, making both harder or impossible to repair. Walk the bike instead. If the tire is only slightly soft, you can ride slowly and carefully to the nearest repair shop, but do not ride at normal speed or on rough terrain.

How do I know what pressure to inflate the tire to?

The correct pressure range is printed on the tire sidewall, usually in psi (pounds per square inch). Road bike tires typically need 80–130 psi, while mountain bike and hybrid tires need 30–50 psi. Inflate to the middle of the range or slightly higher. Use a pump with a pressure gauge so you can see the exact pressure as you inflate.

What if the new tube keeps going flat?

The tire likely still contains the object that caused the first flat. Remove the wheel again, deflate the tube, and inspect the tire interior very carefully, feeling along the entire inside surface. Also check the rim tape — the strip that covers the spoke holes — for damage or missing sections. If the rim tape is torn, spokes can puncture the tube.

Do I need special tools to change a flat?

No. Tire levers, a pump, and a replacement tube are the only tools required. You do not need a wrench if your bike has quick-release levers. A bike stand makes the job easier but is not necessary — you can work with the bike upside down on a clean surface.