What you need before you start

Changing a flat tire requires a tire lever (also called a tire iron), a new inner tube or a patch kit, and a bicycle pump. Tire levers are flat metal or plastic tools that pry the tire bead—the edge of the tire—away from the rim so you can remove the tube. Most bike shops sell tire lever sets of two or three for a few dollars. A new tube costs between $8 and $15 depending on your wheel size. If you want to patch the old tube instead, a patch kit costs $3 to $5 and includes sandpaper, patches, and adhesive.

Before you buy anything, write down your wheel size. Look on the sidewall of your tire; you'll see a number like 26 x 1.95 or 700 x 28c. The first number is the diameter, the second is the width. Tubes are sized to match, so buying the wrong size means a wasted trip. If you're not sure, take a photo of the tire and bring it to the shop.

You'll also need a way to hold the bike steady while you work. A bike stand is ideal, but you can flip the bike upside down so the handlebars and seat rest on the ground. This keeps both hands free.

Key Takeaways

  • Remove the wheel by opening the quick-release lever or unscrewing the axle nuts, then use tire levers to pry the tire bead off the rim on both sides.
  • Pull out the old tube completely, then inspect the inside of the tire for thorns, glass, or sharp objects that caused the flat.
  • Install the new tube by tucking the valve through the rim hole first, then working the tire bead back onto the rim with your hands and tire levers.
  • Inflate the tire to the pressure printed on the sidewall, starting at a low pressure and checking that the bead seats evenly on both sides as you pump.
  • Reinstall the wheel, making sure the brake pads are not rubbing and the quick-release or axle nuts are tight before riding.

Remove the wheel from the frame

Most modern bikes have a quick-release lever on the wheel axle. Open the lever by flipping it outward—it should move freely without forcing. The wheel will loosen but usually stay in place. If your bike has axle nuts instead, use a wrench to unscrew both nuts, turning counterclockwise.

For the front wheel, lift it out of the fork. For the rear wheel, shift the chain to the smallest cog, then pull the derailleur back and lift the wheel out of the chain. Set the wheel on a clean surface so the tire doesn't pick up dirt.

Pry the tire off the rim

Insert a tire lever under the tire bead about 6 inches from the valve. Pry gently until the bead lifts over the rim edge. Hook the other end of the lever to a spoke to hold it in place. Insert the second lever about 12 inches away and repeat. Work your way around the rim, spacing the levers evenly, until one side of the tire is completely off.

You do not need to remove the entire tire. Once one bead is free, you can pull the inner tube out from under the tire. Grasp the valve and pull the tube straight out. If the valve is threaded into the rim, unscrew the locknut first.

Do not pry the second bead off yet. Inspect the inside of the tire carefully, running your fingers along the inner surface. Look for thorns, glass shards, or sharp objects. If you find something, remove it. If you skip this step and install a new tube without finding what caused the flat, you'll get another flat when ready.

Install the new tube

Before you touch the new tube, inflate it slightly—just enough so it holds its shape and doesn't fold on itself. This prevents twisting and pinching during installation. Tuck the valve through the hole in the rim first, then work the tube under the tire bead all the way around the wheel.

Now pry the second bead back onto the rim using your tire levers, working in the same way you removed it. As you get near the end, the tire will become tight and hard to move. This is normal. Use your body weight on the lever rather than your hands alone. If you're stuck, inflate the tube a bit more to help push the bead onto the rim.

Once both beads are seated on the rim, the tire should look even and centered. If one side bulges outward or the tire looks lopsided, the bead is not fully seated. Deflate slightly, work that section with a tire lever, and try again.

Inflate the tire to the correct pressure

The correct pressure is printed on the sidewall of the tire, usually as a range like "80–100 psi" or "2.5–3.0 bar." Start pumping at a low pressure—around 20 psi—and stop to check that the bead is seating evenly on both sides of the rim. The tire should look the same width all the way around. If one side is bulging, deflate, adjust the bead with your hands or a lever, and try again.

Once the bead is seated, continue inflating to the pressure you want. For road bikes, aim for the higher end of the range. For mountain bikes, the lower end gives more traction and comfort. Check the pressure with a floor pump's built-in gauge or a separate pressure gauge.

Reinstall the wheel on the frame

For the front wheel, lower it into the fork and close the quick-release lever. It should require firm pressure to close—if it closes too easily, the wheel is not tight enough. Open it again and tighten the adjustment nut on the opposite side, then try closing the lever again. It should feel snug.

For the rear wheel, pull the derailleur back, guide the chain onto the smallest cog, and lower the wheel into the frame. Close the quick-release or tighten the axle nuts. Spin the wheel to make sure it does not rub on the brake pads. If it does, the wheel is not centered. Loosen it slightly, center it by hand, and tighten again.

Spin both wheels and squeeze the brakes to confirm everything works. You're ready to ride.

When to patch instead of replacing the tube

If you're far from home and don't have a new tube, a patch kit can get you back. Dry the tube completely, use the sandpaper in the kit to roughen the area around the hole, explore the adhesive, wait the time specified on the kit (usually 3 to 5 minutes), and press the patch firmly onto the hole. Hold it for the time listed, then peel off the foil backing.

Patches work best on small holes in the tube body. They are less reliable on holes near the valve or on large tears. If you patch a tube to get home, replace it with a new one before your next ride. A patched tube is a temporary fix, not a permanent solution.

Frequently Asked Questions

How do I know which side of the tire to pry off first?

It does not matter. Start on whichever side is easiest to reach. Most people start opposite the valve because the valve takes up space and makes that side harder to work with.

What if the tire bead won't go back on the rim?

Deflate the tube a little, which reduces pressure pushing the bead outward. Inflate the tube slightly more than you did before, which helps push the bead onto the rim. Work in small sections rather than trying to do the whole tire at once. If you're still stuck, the tire may be too tight for the rim—this is rare, but a bike shop can help.

Can I ride on a patched tube?

A patch is a temporary fix that works for getting home. Patches fail more often than new tubes, especially if the hole is large or near the valve. Replace the tube with a new one before your next ride.

What causes flats, and how do I prevent them?

Thorns, glass, and sharp objects puncture tubes. Pinch flats happen when the tire pressure is too low and the tube gets squeezed between the tire and rim. Check your tire pressure weekly and inflate to the range on the sidewall. Avoid riding through broken glass or over rough ground when possible.

Do I need to remove the wheel to change a tire?

Yes. You cannot pry the tire bead off the rim while the wheel is on the frame because you need access to both sides of the rim and room to work with tire levers.