White Heat Shrink Tubing 3:1 Ratio — Φ1.6mm to Φ30mm Wire Sleeving

Measure the outer diameter of the wire or connector you need to cover, then select a tubing size that is typically 20–30% larger than that measurement before shrinking. For example, a 4mm wire generally works well with Φ4.8mm or Φ6.4mm tubing. With a 3:1 shrink ratio, the tubing will shrink down to roughly one-third of its expanded diameter, so there is plenty of margin for a secure, snug fit.

A 3:1 shrink ratio means the tubing will shrink to approximately one-third of its original expanded diameter when heat is applied. This is generally more versatile than standard 2:1 tubing, making it suitable for irregular shapes, connectors, and bundled cables where a tighter conforming fit is needed. It also means you can use a slightly larger starting diameter and still achieve a secure result.

Polyolefin heat shrink tubing generally offers good resistance to UV exposure, moisture, and mild chemicals, making it suitable for many outdoor and marine wiring applications. For long-term submersion or harsh saltwater environments, we recommend confirming the specific product rating. Contact us to confirm suitability for your environment before ordering.

This tubing typically begins to shrink at around 70–90°C (158–194°F) and achieves full shrinkage at approximately 120°C (248°F). A heat gun is the recommended tool — move it slowly and evenly along the tubing from the center outward to avoid air pockets or uneven shrinkage. Avoid using open flames such as lighters or torches, which can scorch or melt the tubing unevenly.

Yes, polyolefin heat shrink tubing is commonly used in automotive wiring repairs and harness protection. It is generally resistant to engine fluids, vibration, and the temperature fluctuations found in vehicle environments. Select the diameter that fits your wire gauge for a secure, professional finish. For high-heat zones close to exhaust components, contact us to confirm the appropriate rating.

Here are the approximate inch equivalents for each available diameter:

• Φ1.6mm ≈ 1/16"
• Φ2.4mm ≈ 3/32"
• Φ3.2mm ≈ 1/8"
• Φ4mm ≈ 5/32"
• Φ4.8mm ≈ 3/16"
• Φ6.4mm ≈ 1/4"
• Φ7.9mm ≈ 5/16"
• Φ9.5mm ≈ 3/8"
• Φ12.7mm ≈ 1/2"
• Φ15.4mm ≈ 5/8"
• Φ19.1mm ≈ 3/4"
• Φ25.4mm = 1"
• Φ30mm ≈ 1-3/16"

Yes. The tubing can be cut to any length with standard scissors or a utility knife before applying heat. Cut cleanly at a right angle to prevent fraying at the ends. Always apply heat evenly from the center outward to avoid trapping air inside the tubing. Pre-cutting to length before shrinking gives you the cleanest, most professional result.