How to Pick the Right Inner Tube Size

Founder, Mr. Mamil

There are many sizes for inner tubes, such as wheel circumference, tire width, valve length, and valve type. We will get into each of these factors below.

This article will explain the basics of inner tube measurements and how to choose the suitable one for your tire and wheel.

Determine the wheel diameter

The first step is to find out the wheel diameter. Depending on the type of bike, the wheel diameter can range from 10” to 29”.

Type of bikeWheel diameter
Kids10”, 12”, 14”, 16”, 20”, 24”
Mountain26”, 27.5”, 29”
Road, Cyclocross700c (29”)
Gravel650b (27.5”), 700c (29”)
Common wheel diameter for every type of bikes

Determine the tire width

The second step is to determine the tire width to be used with the inner tube. Depending on the type of bike and tires, the width can vary.

Type of bikeTire width
Kids1.5” to 2.5”
Mountain1.5” to 2.75”
Road, Cyclocross21 to 33mm
Gravel30 to 50mm
Common tire widths for every type of bikes

Determine the valve type

The third step is to find out the valve type; Presta or Schrader.

  • Presta valves are slimmer and have a locking nut at the tip.
  • Schrader valves are thicker and don’t have the locking nut. Schrader valves are also used in automobiles.
Type of bikeValve type
MountainSchrader or Presta
Road, CyclocrossPresta
Common valve type for every type of bikes

Determine the valve length

Schrader valves are more straightforward and usually have a length of 40mm.

On the other hand, Presta valves can come in various lengths from 30mm to 100mm. The ideal valve length will depend on the rim’s depth (profile).

Rim profileRim depthValve length
LowBelow 30mm40mm
Mid30 to 50mm60mm
HighAbove 50mm80mm or more
Valve lengths for every rim profiles

How to find the ideal inner tube size

Once you’ve determined the wheel size, tire width, valve type, and length, it’s time to put all these together and shortlist the suitable inner tube.

Inner tube dimensions are denoted by Wheel diameter x Tire width. For example,

  • 27.5 x 1.75 – 2.4”, for a mountain bike with 27.5” wheel diameter and suits tire widths from 1.75” to 2.4”.
  • 700c x 20 – 28mm, for a road bike with a 700c wheel diameter and suits tires from 20 to 28mm wide.
  • 700c x 35 – 44mm, for a gravel bike with a 700c wheel diameter and suits tires from 35 to 44mm wide.

Since the inner tubes can expand and stretch, they tend to suit a range of tire widths. It’s common to find road bike inner tubes in 18 – 28mm, 20 – 28mm, and 28 – 38mm sizes.

Ideally, you want your tire width to fall in the middle of the range.

Once you have nailed down the Wheel Diameter x Tire width, proceed to select the ideal valve length. Most inner tubes have different length variants of the same model.

Choose accordingly.

Alex Lee at Mr.Mamil

Alex Lee is the founder and editor-at-large of Mr. Mamil. Coming from a professional engineering background, he breaks down technical cycling nuances into an easy-to-understand and digestible format here.

He has been riding road bikes actively for the past 12 years and started racing competitively in the senior category during the summer recently.