New tube goes flat soon after fitting a tyre

A new tube or a newly fitted tyre loses air within hours or days. Common causes are a tube pinched by a tyre lever, a spoke end or rough rim edge that cuts it, a leaking valve and a tube that is folded inside the tyre.

Is it safe to ride?

No. A flat or half-flat tyre is not safe. Do not ride on it.

Quick checks first

• Look at the pinch: two small slits side by side on the tube, which is a snake-bite.
• Check the valve with soapy water. Bubbles show a leak.
• Run a hand round the inside of the rim. Feel for a spoke end, rust or a sharp edge.
• Check the rim tape or strip is in place and covers every nipple.

Diagnose it step by step

1Does the tube have two small slits side by side?

• Yes: it was pinched. Either by a lever when the tyre was fitted, or by riding at low pressure. Replace the tube. Fit the tyre in small bites (Make a rounded tyre lever for fitting the last bead).
• No: go to step 2.

2Is there a hole on the inside of the tube, under the rim?

• Yes: a spoke end or nipple is cutting it. File the spoke end flat and fit new rim tape. Duct tape in a few wraps can work as a temporary rim strip. See Check and tighten spokes.
• No: go to step 3.

3Does soapy water on the valve show bubbles?

• Yes: tighten the valve core. If it still leaks, replace the core. A core that leaks in one stem often holds in another. See Check and replace a tyre valve.
• No: go to step 4.

4Is the tyre seated evenly, with the moulded line the same distance from the rim all round?

• No: let the air out, lubricate and refit. The valve must point toward the axle, not tilt.
• Yes: go to step 5.

5Was the tube patched?

• A patched tube is weaker. Replace the tube. Do not rely on a patch for a motorcycle tyre; see Repair a puncture in an inner tube.

Causes, most likely first