Bike Tire Tube Size Chart | What Fits What

A bicycle inner tube must match your wheel diameter and fall inside your tire’s width range, or it won’t fit well.

If you’re buying a spare in a hurry, this Bike Tire Tube Size Chart takes a lot of guesswork off the table. Tube sizing sounds messy at first because bike tires use inch labels, French labels, and ETRTO numbers. Once you know what each number means, the whole thing gets a lot easier.

The main rule is plain: match the wheel diameter first, then match the tire width range. Get the diameter wrong and the tube won’t seat. Get the width wrong and it may stretch too thin, bunch up, or wear out sooner than it should.

How Tube Sizing Works On A Bike

An inner tube is sized by two measurements. One is the wheel diameter. The other is the tire width range that tube can stretch across. Tube boxes often show that as a span, not a single tire size.

Read The Numbers In This Order

Start with diameter. That’s the make-or-break measurement. On a tire sidewall, you may see a familiar shop label like 700 x 35C, 29 x 2.25, or 26 x 1.95. You may also see an ETRTO number such as 37-622.

That ETRTO number is the cleanest way to match parts. In 37-622, the first number is the tire width in millimeters. The second is the bead seat diameter, which tells you the wheel size the tire fits. A tube that matches 622 mm diameter can work with several widths, as long as your tire lands inside the printed width span.

• 700c road, gravel, and many hybrid tires usually use 622 mm diameter.
• 29er mountain tires also use 622 mm diameter.
• 27.5 inch and 650b tires use 584 mm diameter.
• Most classic 26 inch mountain tires use 559 mm diameter.

Why One Tube Can Fit More Than One Tire Width

Butyl tubes stretch, so brands sell them in ranges. A tube labeled 700 x 28-35C might fit a 28 mm road tire, a 32 mm commuter tire, and a 35 mm gravel tire. That’s normal. The safer bet is to stay near the middle of the printed range instead of right at the far edge.

That’s also why you’ll see some tubes labeled for more than one wheel name. A box may say 28/29 because both share the same 622 mm diameter. The width range is what decides whether it fits your tire.

Bike Tire Tube Size Chart By Common Wheel Sizes

Use this chart as a fast shopping shortcut. Then check the tire sidewall before you buy. Tube labels vary a bit by brand, so treat the last column as the kind of size band you’ll usually see, not a hard rule for every box on the shelf.

Wheel Size On Tire	Common Tire Widths	Typical Tube Size Range To Buy
12 inch	1.75–2.125	12 x 1.75–2.125
16 inch	1.75–2.125	16 x 1.75–2.125
18 inch	1.75–2.125	18 x 1.75–2.125
20 inch BMX / kids	1.50–1.95	20 x 1.50–1.95
20 inch wide / BMX	1.75–2.40	20 x 1.75–2.40
24 inch	1.75–2.125	24 x 1.75–2.125
26 inch MTB	1.75–2.125	26 x 1.75–2.125
27.5 inch / 650b	2.10–2.40	27.5 x 2.10–2.40
700c road	23–28 mm	700 x 23–28C
700c all-road / gravel	28–45 mm	700 x 28–45C
29 inch MTB	2.10–2.40	29 x 2.10–2.40

The chart gets you close fast. The tire sidewall gives you the final answer. If the tube’s printed width span includes your tire width and the diameter matches, you’re in good shape.

How To Match The Right Tube In Under A Minute

You don’t need a measuring tape. You just need the markings already printed on the tire.

Step 1: Find The Sidewall Size

Look along the tire sidewall for the full size marking. You may see two systems on the same tire. A gravel tire might read 700 x 40C and 40-622. A mountain tire might read 29 x 2.25 and 57-622. If both are there, use the ETRTO number as your tie-breaker. Schwalbe’s tire sizing page lays out why that numbering system clears up the old inch-label confusion.

Step 2: Match Diameter First, Width Second

This is where wrong purchases happen. A 700c tube and a 27.5 tube are not close cousins. They use different diameters, so they do not swap. A 700c tube and a 29er tube often can swap, because both use 622 mm diameter, but the width range still has to match your tire.

Say your tire reads 700 x 32C. A tube marked 700 x 28-35C works. A tube marked 700 x 18-25C is too narrow. A tube marked 29 x 2.2-2.4 is built for the same diameter but a much wider tire, so it’s a poor match.

Step 3: Pick The Valve That Fits Your Rim

Tube size is only half the buy. Valve type matters too. Most road, gravel, and many modern mountain bikes use Presta valves. They’re slim and fit the smaller hole found in many bike rims. Schrader valves are the car-style valves seen on plenty of kids’ bikes, hybrids, and older mountain bikes. Some city bikes use Dunlop valves.

Valve length also matters on deep-section rims. If the valve barely sticks through the rim, pump heads can be a pain to attach. On normal alloy rims, standard Presta length is usually fine. On deep aero rims, you may need a longer valve.

Look-Alike Sizes That Catch People Out

Bike sizing names can look close and still mean different things. That’s why the ETRTO number on the sidewall matters so much.

Sizes You May See	Same Diameter?	What To Check
700c and 29 inch	Yes, both use 622 mm	Match the tube width range to your tire width
27.5 inch and 650b	Yes, both use 584 mm	Width still has to match
26 x 1 3/8 and 26 x 1.75	No	Check the ETRTO number before buying
650c and 26 inch	No	Use bead seat diameter, not the name alone
20 x 1 1/8 and 20 x 1.75	Often no	Kids and BMX sizes vary more than many riders expect

One extra wrinkle: 26 inch is not one single size family. That old label covers several different bead seat diameters. If you’re working on a vintage bike, a city bike, or a kid’s bike, trust the ETRTO marking over the inch label every time.

What To Check Before You Install The Tube

A fresh tube won’t solve a bad tire, a split rim tape, or debris still stuck in the casing. If you skip those checks, the new tube can pop in the same ride.

Give The Tire And Rim A Fast Once-Over

• Run your fingers along the inside of the tire and pull out glass, wire, or thorns.
• Check the rim tape. If spoke holes peek through, swap the tape before fitting the tube.
• Make sure the tire bead sits evenly all the way around the rim.
• Add a small puff of air to the tube before installation so it holds its shape.

Continental’s ETRTO standards note also points riders back to tire and rim compatibility, printed pressure limits, and the need to follow the lower limit if tire and rim numbers differ. That last check matters most on narrow road setups and modern wide rims.

Best Way To Buy A Spare Tube

If you want one spare to carry on every ride, buy the tube that matches the tires currently on the bike, not the tire width you may switch to later. Keep the spare in a small bag with tire levers and a patch kit. Tubes get old, so don’t leave one rattling around for years in heat and sun.

When you shop, bring these three details:

• The full tire size from the sidewall
• The valve type already on the bike
• The valve length if you ride deep rims

That small note on your phone can save you from the most common mix-up: buying a tube that sounds right by name but misses the real diameter stamped on the tire.