What you need before you start

Changing a bicycle tyre requires a tyre lever (or two), a new tyre or inner tube, and a pump. A tyre lever is a flat tool, usually plastic or metal, that hooks under the tyre bead—the edge that sits on the rim—and lifts it away so you can remove the old tube or tyre. Most bike shops sell lever sets for a few pounds; some riders keep two or three in a saddlebag because they can bend or snap under pressure.

Before you buy a replacement, check the size printed on the side of your old tyre. It will look like "700 x 25c" or "26 x 1.95"—the first number is the wheel diameter, the second is the width. Your new tyre must match these measurements exactly. If you are replacing the inner tube only (the most common repair), you need a tube in the same size with a valve that matches your rim: either Presta (thin, with a small nut) or Schrader (wider, like a car tyre valve).

Key Takeaways

  • Check the tyre size printed on your old tyre before buying a replacement—it must match exactly.
  • Use a tyre lever to hook under the tyre bead and lift it away from the rim without pinching the new tube.
  • Inflate the new tube slightly before fitting it so it holds its shape and does not twist inside the tyre.
  • Seat the tyre bead evenly on the rim all the way around before inflating to full pressure, or the tyre will bulge unevenly.
  • If the tyre will not come off, try letting air out of the old tube completely and working the lever around the rim in small sections.

Removing the old tyre and tube

Start by letting all the air out of the old tube. Unscrew the valve cap and press the valve stem to release any remaining pressure. This makes the tyre soft and easier to work with.

Insert the flat end of a tyre lever under the tyre bead—the edge of the tyre that sits on the rim—about 15 centimetres away from the valve. Hook the lever to the rim and pry the bead up and over the edge. Once you have lifted one section, slide the lever around the rim to free one side of the tyre completely. The other side usually stays on the rim; you do not need to remove it.

Pull the old inner tube out from inside the tyre. If you are replacing the tyre as well as the tube, use the lever to pry the second bead off the rim. Work slowly and use two levers if the tyre is tight—one to hold the bead up while you move the other around the rim. Pinching the new tube with the lever is the most common mistake at this stage, so take your time.

Fitting the new tube and tyre

Before you fit the new tube, inflate it slightly—just enough so it holds its shape and does not fold or twist. A tube that is completely flat will bunch up inside the tyre and pinch when you inflate the wheel, creating a flat spot or a slow leak.

Fit the valve through the rim hole first. Then tuck the tube evenly inside the tyre all the way around, making sure it does not twist and sits flat against the rim. This step matters: a twisted tube will pinch and fail.

Starting opposite the valve, use your hands to push the tyre bead back onto the rim. Work your way around, pushing the bead down and inward with the heel of your hand. When you reach the last section near the valve, the tyre will be tight; push hard and roll the bead onto the rim. If the tyre will not go on, let a little more air out of the tube and try again. Do not use the lever to force the bead on—you risk pinching the tube.

Seating the bead and inflating

Before you inflate to full pressure, check that the tyre bead is seated evenly on the rim all the way around. Look at the thin line where the tyre meets the rim; it should be the same distance from the rim edge everywhere. If one section is higher or lower, the tyre is not seated properly and will bulge when you inflate it.

If the bead is not even, let the air out again, work that section with your hands, and re-seat it. Once the bead looks even, inflate slowly to about half pressure and check again. The bead should stay in place as you add air. Inflate to the pressure printed on the tyre sidewall—usually between 80 and 130 psi depending on the tyre width and your weight.

Spin the wheel and watch the bead line again. It should stay the same distance from the rim all the way around. If it wobbles, stop, let air out, and re-seat that section.

Troubleshooting a stuck tyre

If the old tyre will not come off, the bead is probably stuck to the rim. Let all the air out completely and wait a few minutes. The rubber will relax slightly. Then work the lever around the rim in small sections—do not try to pry the whole bead off at once. Push the bead inward with your hand first, then use the lever to lift just a small section at a time.

If the tyre is still stuck, try breaking the bead by rolling the wheel on the ground with your weight on it, or by carefully tapping the tyre sidewall with a rubber mallet. This loosens the seal between the tyre and rim. Once the bead moves, the lever will work more easily.

On the other end, if the new tyre is very tight and will not roll onto the rim by hand, inflate the tube inside it to about 40 psi first. This pushes the tyre outward and makes it easier to work the bead onto the rim. Then deflate slightly, re-seat the bead, and inflate to full pressure.

When to replace the tyre instead of just the tube

Most punctures are fixed by replacing the inner tube only. The tyre itself can last for years if the rubber is not cracked, worn smooth, or damaged. Check the old tyre before you throw it away: if the tread is still visible and the sidewalls are not split or bulging, you can reuse it with a new tube.

Replace the tyre if the tread is worn flat, if you see cracks in the rubber, if the sidewall is split or has a bulge, or if there is a hole or cut in the tyre itself. A damaged tyre will fail again even with a new tube inside it. If you are unsure, take the wheel to a bike shop and ask—they can tell you in seconds whether the tyre is safe to reuse.

Frequently Asked Questions

How do I know if I need to replace the tyre or just the tube?

Most punctures only damage the tube. Check the old tyre for cracks, bulges, or worn-smooth tread. If the rubber looks intact and the tread is still visible, you can reuse the tyre with a new tube. If the tyre has a hole, split, or flat worn spot, replace it.

What if I pinch the new tube while fitting it?

You will usually hear or feel a small pop. If this happens, take the tyre off again, remove the damaged tube, and start over with a fresh one. Pinched tubes fail quickly, so do not try to patch and reuse them. This is why inflating the new tube slightly before fitting it helps—a firm tube is harder to pinch.

Can I use a tyre lever on a carbon rim?

Carbon rims are more fragile than aluminium. Use plastic tyre levers only, never metal ones. Metal levers can crack the rim. If the tyre is very tight on a carbon rim, inflate the tube inside it slightly to push the tyre outward, then work the bead off by hand rather than with a lever.

Why does my new tyre bulge on one side after I inflate it?

The bead is not seated evenly on the rim. Let air out, check the bead line all the way around, and re-seat any section that is too high. Inflate slowly and watch the bead as you add pressure. Once the bead is even, the tyre will inflate symmetrically.

How tight should I inflate the new tube before fitting the tyre?

Just enough so the tube holds its shape and does not fold—roughly 20 to 30 psi. You are not aiming for full pressure yet; you just want the tube firm enough that it will not twist or bunch inside the tyre when you work the bead onto the rim.