How to Measure a Rim for Tubeless Rim Tape
Choosing the right tubeless rim tape starts with one simple measurement: your rim’s internal width. If the tape is too narrow, spoke holes may remain exposed and cause air leaks. If it is too wide, it can interfere with the tyre bead and make installation difficult.
This guide explains how to measure rim width for tubeless tape, how to choose the correct tape size, and how to install it properly.
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What You Need to Measure a Rim
You do not need many tools. Keep these items ready:
- Digital caliper for accurate measurement
- Steel ruler if you do not have a caliper
- Isopropyl alcohol for cleaning the rim
- Clean cloth or rag
- Flashlight for checking the rim bed and spoke holes
For the most accurate result, a digital caliper is the best option.
How to Measure Rim Width for Tubeless Tape
The measurement you need is the internal rim width. This is the distance across the inside of the rim where the tyre sits.
Do not measure the outside width of the rim. External width and internal width are different, and using the wrong measurement can result in incorrectly sized rim tape.
Step 1: Find the Internal Rim Width
Remove the tyre and inspect the rim bed. You need to measure across the internal channel from one bead seat to the other.
Place the measuring tool at the points where the tyre bead sits.
Step 2: Measure with a Digital Caliper
- Open the caliper and place its jaws against the inside edges of the rim.
- Gently close the jaws until they touch both sides without squeezing the rim.
- Read the measurement in millimetres.
For example, if your rim measures 23 mm internally, your starting point for tape selection would normally be a tape around 25 mm wide, depending on the rim and tape manufacturer's recommendation.
Step 3: Use a Ruler If You Do Not Have a Caliper
A steel ruler can be used when a digital caliper is unavailable.
Place the ruler across the internal rim channel and measure from one inside edge to the other. Keep the ruler straight and make sure you are measuring the internal width rather than the external width.
This method is less precise, so a caliper is preferable when possible.
Step 4: Check the Rim Manufacturer's Specification
Before buying tape, check whether the rim manufacturer lists its internal width.
The specification may be printed on the rim, included in the wheel documentation, or available on the manufacturer's website.
If the manufacturer's recommended tape size differs from the general sizing rule, follow the manufacturer's recommendation.
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How Wide Should Tubeless Rim Tape Be?
As a general starting point, tubeless rim tape is commonly selected slightly wider than the rim's internal width.
A difference of around 1–2 mm wider is often recommended, but the exact requirement depends on the rim design and tape manufacturer.
Internal Rim Width |
Typical Tape Starting Point |
|
17 mm |
19 mm |
|
18–19 mm |
21 mm |
|
20–21 mm |
23 mm |
|
22–23 mm |
25 mm |
|
24–25 mm |
27 mm |
|
26–28 mm |
29 mm |
|
29–30 mm |
32 mm |
|
31–35 mm |
37 mm |
|
38–40 mm |
42 mm |
These measurements are a practical reference, not a universal rule. Some manufacturers recommend tape that is wider than this, particularly for certain MTB and tubeless rim designs.
What Happens If Tubeless Tape Is Too Narrow?
Tape that is too narrow may fail to cover the entire rim bed or spoke holes.
This can result in:
- Slow air leaks
- Sealant leaking into the rim
- Difficulty maintaining tyre pressure
- Tubeless setup failure
If you notice air escaping around the spoke holes after installation, incorrectly sized or poorly installed tape can be one possible cause.
What Happens If Tubeless Tape Is Too Wide?
Using tape that is excessively wide can also cause problems.
It may climb the rim walls and interfere with the tyre bead. This can make the tyre harder to install or prevent the bead from seating correctly.
The goal is complete coverage of the rim bed without interfering with the bead seat.
Do You Need One or Two Layers of Tubeless Tape?
For most setups, one good-quality layer of tubeless rim tape is enough when the correct tape is used and installed properly.
A second layer may be useful when:
- The rim has deep or recessed spoke holes
- Additional protection is required
- The manufacturer recommends multiple layers
- Your particular setup requires additional thickness
Do not automatically add multiple layers. Too much tape can make tyre installation and bead seating more difficult.
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How to Install Tubeless Rim Tape Correctly
Once you have selected the correct tape width, installation is just as important as measurement.
1. Clean the Rim
Remove old tape and clean the rim bed thoroughly with isopropyl alcohol.
Allow the surface to dry completely before applying new tape.
2. Start Near the Valve Hole
Begin applying the tape near the valve hole while keeping consistent tension.
Work around the rim and press the tape firmly onto the rim bed.
3. Keep the Tape Centred
Make sure the tape remains centred throughout the rim.
It should cover the required area without climbing too far up either side of the rim.
4. Overlap the Tape
When you reach the starting point, create a suitable overlap rather than leaving a gap.
Press the overlapping section firmly so that the tape forms a continuous seal.
5. Create the Valve Hole
After the tape is securely installed, make a small, clean opening for the tubeless valve.
Avoid cutting a large hole because it can compromise the seal around the valve.
Common Tubeless Rim Tape Mistakes
Mistake |
Why It Causes Problems |
|
Measuring external rim width |
Gives the wrong tape size |
|
Choosing tape that is too narrow |
May leave spoke holes exposed |
|
Choosing tape that is too wide |
Can interfere with the tyre bead |
|
Installing tape over a dirty rim |
Prevents proper adhesion |
|
Leaving gaps in the tape |
Can cause air leakage |
|
Making an oversized valve hole |
Can create sealing problems |
|
Using unsuitable tape |
May fail under pressure or sealant |
How Do You Know What Size Rim Tape You Need?
The easiest method is:
Measure your rim's internal width in millimetres, then check the tape manufacturer's sizing recommendation.
For example:
- 20 mm internal rim → around 22 mm tape may be suitable
- 23 mm internal rim → around 25 mm tape may be suitable
- 25 mm internal rim → around 27 mm tape may be suitable
- 30 mm internal rim → around 32 mm tape may be suitable
Always check the specific rim and tape manufacturer's recommendations before purchasing.
Quick Checklist
Before installing tubeless rim tape, make sure you:
- Remove the tyre and old tape.
- Clean and dry the rim bed.
- Measure the internal rim width.
- Check the wheel manufacturer's recommendation.
- Select the appropriate tape width.
- Apply the tape evenly and under consistent tension.
- Ensure there are no gaps or exposed spoke holes.
- Create a clean valve opening.
- Install the tubeless valve and tyre.
- Inflate and check carefully for air leaks.
FAQ
How do I measure a rim for tubeless tape?
Measure the internal width of the rim from one inside bead seat to the other. A digital caliper provides the most accurate measurement.
Should tubeless rim tape be wider than the rim?
Usually, yes. A common starting point is 1–2 mm wider than the internal rim width, but manufacturer recommendations can vary.
What size tape do I need for a 25 mm rim?
A 27 mm tape can be a suitable starting point for a 25 mm internal rim, provided it matches the rim manufacturer's requirements.
Can I use tape that is exactly the same width as my rim?
It may work with some rim designs, but slightly wider tape is commonly preferred to ensure proper coverage. Always follow the tape and rim manufacturer's specifications.
What happens if tubeless rim tape is too narrow?
It may not completely seal the rim bed and spoke holes, resulting in air leaks or sealant escaping into the rim.
How do I know my rim size?
Check the manufacturer's markings or specifications, or measure the rim's internal width directly with a digital caliper after removing the tyre.
Is one layer of tubeless rim tape enough?
For most standard setups, one properly installed layer is sufficient. Some rims or high-pressure applications may require additional layers according to the manufacturer's instructions.
Can I install tubeless rim tape myself?
Yes. With the correct tape, a clean rim, and careful installation, many cyclists can install tubeless rim tape themselves. The most important steps are getting the width right and creating a complete, airtight seal.