700x38c Inner Tube Conversion (Simple Answer)

Photo of author

Ben Jones

Accessories, Components, Maintenance, Resources


Disclosure: I may receive referral fees from purchases made through links on BicycleVolt. As an Amazon Associate, I earn from qualifying purchases.

The simple answer is:

700x38c converts to around 27.5” x 1.5”.

The even simpler answer is to stick with the 700x38c sizing and buy a tube that’s labeled with that size. We’ll take a look at why this is so important in a moment.

My recommendations:

Inner tube recommendation:

This is an excellent inner tube that has a Presta valve fitted. Easy to install and great value.

Presta valves are different to the standard valves that you get on car (auto) tires. They’re quite a bit slimmer and lengthier than Schrader valves (the technical name for car tire valves).

If you’ve got an air pump that fits car tires you’ll also need to get yourself a small convertor for use on Presta valves.

Easy to use, just screw them onto the valve and you can use the same pump for both types of valve in the future.

READ THIS NEXT The 2 main types of bike tire valves and how they work

Let’s get a little more detail behind the simple explanation

700x38c is the bike tire size, measured according to an antiquated ‘French system’.

‘700’ is the tire’s diameter (in millimeters).

‘x’ is multiplied by.

‘38’ is the approximate tire width (in millimeters).

‘c’ is the width code for the tire, in the French system. Whilst still frequently seen, nowadays it’s a term that’s pretty much obsolete. In France, it was previously used to categorize tires from narrowest (‘a’) to widest (‘d’). Therefore, a ‘c’ would have been almost as wide as tires got.

Would you also like a tire recommendation for your 700x38c bike? Then read on!

READ THIS NEXT What Size Bicycle Tire Tube Do I Need? (Fast Answer)

Do you also need a bike tire to go along with your tube?

The simple rule here is to choose a new tire that says it is “700x38c”. It’s no more complicated than that. Even less complicated than choosing a tube!

There can be a huge amount of variability when it comes to tire sizing and your best approach is always to choose the same tire size code as you have on your wheel currently. Never ever attempt to swap from millimeters to inches or vice versa. You can find massive differences sometimes between the actual size of tires that ‘should’ be the same. Size differences, big or small, can cause big problems, like punctures, along the road.

This is a great quality pair of tires from a well-respected manufacturer. They have a fantastic range and this tire is a very good example.

It’s the perfect size for your bike and gets excellent feedback from buyers for being smooth and fast-rolling, and suitable for a range of terrain.

Take a closer look at the tread pattern and you will see that these tires have a fairly solid strip of rubber along the center with a more open grip pattern along the sides. This is a great combination for your bicycle as it means that the tires will fantastically well on a wide range of different surfaces. On smooth paths and paved roads, they’ll roll fast with virtually no vibration. Then on looser gravel or dirt surfaces the sides will bite into the ground and give you excellent cornering ability.


  • Great value hybrid tire
  • Smooth strip for fast rolling on paved surfaces
  • Excellent cornering on loose dirt and gravel
  • Manufacturer with superb pedigree

READ THIS NEXT 700x38c Tire Size In Inches? (Here’s The Answer)

Now, how about a recap on changing a bike tube?

Firstly, you’ll require some basic items of kit whenever you set out on your bike:

  • Spare tubes (I normally take two)
  • Small tire repair kit
  • Plastic tire levers
  • Air pump (remember the Presta tire valve adaptor I talked about earlier)

The process of swapping an inner tube should then take around 3/4hr to carry out. There are just five simple steps to fixing a flat tube:

Remove the wheel
Take off the inner tube
Determine the cause of the puncture (such as a thorn or piece of glass)
Either repair or replace the inner tube (I generally replace, so I know there’s no other problem that I’ve missed with the old tube)
Bolt the wheel back on

For a simple guide, take a look at this video.

2 thoughts on “700x38c Inner Tube Conversion (Simple Answer)”

Leave a Comment