Ultimate Automotive Wire Comparison: Top 7 Wire Types for Performance, Racing & OEM
Introduction: Which automotive wire should you use for your build?
Automotive wire is the lifeblood of your vehicle’s electrical system. But not all automotive wire is created equal. From factory-spec PVC-insulated conductors to aerospace and military grade ultra-lightweight Tefzel race wire, your choice depends on temperature demands, routing flexibility, durability, and seal compatibility.
This guide compares 7 commonly used automotive wire types, highlighting which are suitable for standard builds, DIY projects, and professional motorsport.
General Use vs. Professional-Grade Automotive Wire
Before diving into the specific types, it’s important to understand this distinction:
- General Automotive Wire: Includes TXL, AVSS, and FLRY. Suitable for OEM, street, and entry-level racing applications.
- Professional-Grade Wire: Includes Spec 44, Spec 55, M22759/32, and M22759/16. These are designed for high-heat, high-vibration, and weight-sensitive environments, such as aerospace and top-tier motorsport.
TXL, AVSS, FLRY – Common in OEM and General Motorsport
TXL wire - photo credit ProWireUSA
TXL (Thin Wall Cross-Linked Polyethylene)
- Temp Rating: -51°C to +125°C
- Insulation: XLPE
- Applications: Aftermarket looms, entry-level motorsport builds
- Pros: Good heat and oil resistance, easy to strip with inexpensive tools
- Cons: Large diameter. Difficult to source outside USA
- Wire diameter 20 AWG (0.5mm²) - 1.78mm
TXL is widely used in America for its availability, affordability and flexibility.
AVSS (Automotive Vinyl Standard Small)
- Temp Rating: Up to 80°C
- Insulation: Thin-wall PVC
- Applications: Japanese OEM harnesses, entry-level motorsport builds
- Pros: Great reliability, insulation diameter suits common wire seals, easy to strip with inexpensive tools
- Cons: Limited high-temp resistance, can be difficult to source in small quantities
- Wire diameter 0.5mm² (20 AWG) - 1.65mm
AVSS is the go-to wire in Japanese vehicles and is used in some of the Link flying lead looms. More details on AVSS can be found here
FLRY-A / FLRY-B (German OEM Standard)
- Temp Rating: Up to 105°C
- Insulation: PVC
- Applications: European vehicles, entry-level motorsport builds
- Pros: Cost-effective, widely available, easy to strip with inexpensive tools
- Cons: Poor resistance to extreme environments
- Wire diameter 0.5mm² (20 AWG) - 1.6mm
FLRY wires are used in Euro-spec OEM vehicles and are common in basic racing and tuning builds throughout Europe.
Spec 44/55 – True Professional-Grade Automotive Wire (The wire EP Wiring uses)
Only two wires make the cut for true professional motorsport-grade applications: TE Spec 44 and TE Spec 55. These wire can be found in F1, WRC, endurance racing, military/defence and aerospace environments.
We mostly use Spec 44 for our wiring harnesses along with Spec 55 for 16 AWG and 10 AWG as these are thinner than the Spec 44 counterparts but are large enough for ease of sourcing wire seals. We would probably use all Spec 55 if we could source the correct wire seals but some series of connectors do not have suitable wire seals for under 1.4mm diameter wire.
TE Spec 44 (Raychem)
- Temp Rating: -65°C to +150°C
- Voltage Rating: 600V
- Insulation: Dual-wall (polyalkene inner, PVDF outer)
- Pros: Flame-retardant, highly durable, seal-friendly OD
- Cons: Slightly heavier than Spec 55, more expensive than general purpose wire, difficult to strip without expensive wire strippers
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Wire diameter 20 AWG (0.5mm²) - 1.4mm
Spec 44 is sometimes selected in motorsport because its outer diameter, while thin, closely matches PVC wires, making it compatible with most automotive connectors and wire seals. It balances performance with ease of integration.
TE Spec 55 (Raychem)
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Temp Rating:
- -65°C to +150°C [-85°F to +302°F] (Tin plated conductor)
- -65°C to +200°C [-85°F to +392°F] (Silver or nickel plated conductor)
- Voltage Rating: 600V
- Insulation: Single or Dual-wall with thinner outer layer. Tefzel (modified radiation cross-linked ETFE polymer)
- Pros: Ultra-lightweight, very small diameter, highest thermal resistance
- Cons: Smaller OD may require custom seals or back shells, more expensive than general purpose wire, difficult to strip without expensive wire strippers
- Wire diameter 20 AWG (0.5mm²) - 1.27mm
This wire is used in high end racing harnesses where reliability and every gram matters. It's ideal for applications near turbo components, exhausts, and engine bays.
M22759/32 and M22759/16 – Military-Grade, Motorsport-Tested
Originally designed for military aerospace, these wires are now staples in high end race builds.
M22759/32 - Essentially identical to Spec 55 (55A0111)
- Temp Rating: -65°C to +150°C
- Insulation: Single layer Tefzel (modified radiation cross-linked ETFE polymer)
- Conductor: Silver-plated copper
- Pros: Ultra-lightweight, very small diameter, highest thermal resistance
- Cons: Small OD may require special seals, more expensive than general purpose wire, difficult to strip without expensive wire strippers
- Wire diameter 20 AWG (0.5mm²) - 1.27mm
Often seen in aircraft, military and top-tier endurance racers, this wire provides the best of both worlds - lightweight construction with exceptional electrical stability.
M22759/16
- Temp Rating: -65°C to +150°C
- Insulation: PTFE
- Pros: High temp capacity, chemical-resistant
- Cons: Heavier than /32, more expensive than general purpose wire, difficult to strip compared to PVC/TXL but easier than Spec 44/55 and /32
- Wire diameter 20 AWG (0.5mm²) - 1.52mm
Used in both military and motorsport, it’s thicker and slightly heavier than /32, similar diameter to common PVC wire.
FAQs: Automotive Wire Comparison
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What’s the best wire for a race car harness?
Use Spec 44 or M22759/16 for ease of compatibility with common wire seals, or Spec 55 or M22759/32 for maximum performance and weight savings. -
Are TXL, FLRY and AVSS safe for race use?
Yes - of course at the top levels of motorsport you may find reliability issues due to extreme heat and vibration. It's worth mentioning that many supercars are manufactured using these grades of wire. -
Why is Spec 44 of /16 wire better for connectors and seals?
It closely mimics PVC wire outer diameter, making it fit OEM-style terminals without modification. -
Do I need motorsport wire for a street car?
Only if you're operating in high-heat environments or want the absolute best performance. TXL, AVSS or FLRY are all sufficient and widely used.