Tefzel Wire
Tefzel wire is the standard choice for professional motorsport wiring harnesses. The insulation material is ETFE (ethylene tetrafluoroethylene) — a fluoropolymer related to PTFE, but lighter and with better mechanical toughness. In motorsport and mil-spec applications, cross-linked modified ETFE is used: radiation cross-linking tightens the polymer structure, improving abrasion resistance and cut-through performance without adding weight.
The primary mil-spec designation is MIL-DTL-22759/32 (SAE AS22759/32). Raychem (now TE Connectivity) manufactures the same wire under the brand name Spec55, part series 55A0111. Both names refer to the same specification: tin-plated annealed copper conductor, cross-linked modified ETFE insulation, rated to 150°C and 600 V.
Note: “Spec55” is a TE Connectivity product family that covers multiple SAE AS22759 sub-specifications. XTRA Motorsport stocks M22759/32 — the thin-wall, tin-plated, 150°C variant. For the silver-plated 200°C variant (also sometimes called Spec55 by builders), see the sub-specification section below.
M22759/32 Wire Specifications
| Property | Value |
|---|---|
| Insulation material | Cross-linked modified ETFE (Tefzel) |
| Conductor | Tin-plated annealed copper, 19-strand (12 AWG: 37-strand) |
| Insulation wall thickness | 0.127 mm (0.005 in) minimum |
| Voltage rating | 600 V RMS |
| Temperature range | −65°C to +150°C continuous |
| Temperature ageing test | 300°C for 7 hours — no insulation failure (per AS22759) |
| Impulse dielectric test | 8.0 kV peak — 100% production tested |
| Insulation resistance | ≥5,000 MΩ per 1,000 ft |
| Flame retardant | Yes — ETFE is self-extinguishing |
| Chemical resistance | Gasoline, avgas, diesel, lubricating oils, hydraulic fluid, high-pH cleaning agents |
| ETFE tensile strength | 38–48 MPa (vs 13–25 MPa for PTFE — approx 34% stronger) |
| RoHS | Compliant |
| Colour code standard | MIL-STD-681 |
| Equivalent brand name | Raychem Spec55, part series 55A0111 |
| SAE specification | SAE AS22759/32 |
AWG Reference Table
Per SAE-AS22759/32 (OD values are min–max per specification). Working current is the recommended safe continuous load for a single conductor in free air with a 30°C temperature rise above ambient — derived from the Marmon Aerospace & Defense ampacity table. Bundle derating: ×0.72 for 3 conductors, ×0.53 for 7 conductors. DC resistance values per MIL-DTL-22759/32 (maximum, at 20°C).
| AWG | Stranding | OD min–max (mm) | Conductor (mm²) | Weight (g/m) | DC resistance (Ω/1000ft) | Working current |
|---|---|---|---|---|---|---|
| 12 | 37/28 | 2.54–2.69 | 3.31 | 29.3 | 2.02 | 27 A |
| 14 | 19/27 | 2.08–2.24 | 2.08 | 19.3 | 3.06 | 21 A |
| 16 | 19/29 | 1.68–1.78 | 1.31 | 12.4 | 4.81 | 15 A |
| 18 | 19/30 | 1.47–1.57 | 0.82 | 9.7 | 6.23 | 13 A |
| 20 | 19/32 | 1.22–1.32 | 0.52 | 6.4 | 9.88 | 10 A |
| 22 | 19/34 | 1.04–1.14 | 0.33 | 4.2 | 16.2 | 8 A |
| 24 | 19/36 | 0.89–0.99 | 0.21 | 3.0 | 26.2 | 6 A |
| 26 | 19/38 | 0.76–0.86 | 0.13 | 2.1 | 41.3 | 4 A |
Part number suffix: M22759/32-{AWG}-{colour} and Spec55 55A0111-{AWG}-{colour}, where colour follows MIL-STD-681: 0=Black, 1=Brown, 2=Red, 3=Orange, 4=Yellow, 5=Green, 6=Blue, 7=Violet, 8=Grey, 9=White. Two-digit suffix (e.g. -09) = white with black stripe.
AWG Selection by Circuit Type
- CAN bus (CAN High / CAN Low): use Spec55 twisted CAN wire (55A0121) — twisted pair construction is required for CAN, not single-core
- Sensor signals, lambda, MAP, TPS, speed sensors: 22–24 AWG
- ECU digital inputs / outputs, injector triggers: 22 AWG
- Injectors: 22 AWG
- Solenoids, small relays: 20–22 AWG
- Cooling fans, fuel pumps, high-current relay outputs: 14–16 AWG
- Main power distribution, high-current feeds: 12 AWG
- Shielded trigger and knock sensor wiring: use M27500 shielded wire — M27500 uses M22759/32 conductors with an aluminium foil shield
M22759 Sub-Specifications
The SAE AS22759 family contains multiple sub-specifications. The difference that matters most for motorsport is conductor plating and temperature rating:
| Spec | Conductor plating | Insulation wall | Temp rating | Typical OD at 22 AWG | XTRA stock | Primary use |
|---|---|---|---|---|---|---|
| M22759/16 | Tin | 0.013 in (thick) | 150°C | ~1.35 mm | No | OEM seal compatibility, abrasion-prone zones, street builds requiring standard seal bore fit |
| M22759/32 | Tin | 0.005 in (thin) | 150°C | 1.04–1.14 mm | Yes | Professional motorsport harnesses — Autosport, Souriau, Deutsch connectors |
| M22759/33 | Silver | 0.006 in | 200°C | similar to /32 | No | 200°C zones, enhanced flex life |
| M22759/44 | Silver | 0.005 in | 200°C | similar to /32 | No | Near-exhaust routing, weight-critical 200°C builds — often called “Spec55 200°C” |
Practical note: When motorsport engineers say “Spec55,” they may mean M22759/32 (the Raychem product name for the 150°C tin-plated variant) or M22759/44 (the 200°C silver-plated variant). For most ECU harness work, M22759/32 at 150°C is sufficient. Route away from exhaust and turbo outlet heat sources; for circuits that must pass through high-heat zones, specify M22759/44.
M22759/16 vs /32 — the OEM seal question: M22759/16 at 22 AWG (~1.35 mm OD) is close to typical OEM rubber wire seal bore sizes, making it a drop-in fit for factory connectors. M22759/32 at 22 AWG (1.04–1.14 mm) is thinner — it may need a short sleeve of Raychem SCL heat shrink to build up OD at an OEM seal. In motorsport connectors (Autosport, ASL, Souriau 8STA, Deutsch DT/AS), /32 fits correctly without modification.
M22759/32 vs TXL Wire
TXL (SAE J1128) is the standard wire for OEM automotive wiring harnesses. The comparison below is for 22 AWG, the most common gauge in motorsport ECU harnesses.
| Property | M22759/32 (Tefzel) | TXL (SAE J1128) |
|---|---|---|
| Standard | SAE AS22759/32 | SAE J1128 |
| Insulation | Cross-linked ETFE | Cross-linked polyethylene |
| Temperature | 150°C | 125°C |
| OD at 22 AWG | 1.04–1.14 mm | ~1.57 mm |
| Weight at 22 AWG | 4.2 g/m | ~5.95 g/m |
| Weight saving at 22 AWG | — | M22759/32 is ~29% lighter |
| Conductor | Tin-plated Cu | Bare Cu |
| Abrasion resistance | Excellent (cross-linked ETFE) | Good |
| Crimp terminal compatibility | Autosport, ASL, ASU, Souriau 8STA, Deutsch DT/AS/DTP | OEM automotive crimp terminals |
| Motorsport harness use | Professional sealed harnesses | Street builds, cost-sensitive builds |
For a 200-circuit harness with an average 1.5 m per circuit, substituting M22759/32 for TXL at 22 AWG saves approximately 500 g — meaningful for a club or professional racing build.
Wire by Gauge
- 12 AWG Tefzel Wire — White, Black, Red
- 14 AWG Tefzel Wire — White, Black, Red
- 16 AWG Tefzel Wire — White, Black, Red
- 18 AWG Tefzel Wire — White, Black, Red
- 20 AWG Tefzel Wire — multiple colours
- 22 AWG Tefzel Wire — 10 colours, most popular
- 24 AWG Tefzel Wire — 10 colours
Ordering Notes
Per metre: Ordering by the metre gives one continuous cut length — not separate pieces. 5 m ordered = one 5 m length, hand-wound loose.
Full spools: Factory spools are supplied wound. Contact us for spool pricing on high-volume requirements.
Working out how much to order? Our step-by-step guide to building a motorsport wiring loom covers measuring and planning runs, gauge selection per circuit, and the crimping and sealing steps that follow — useful for sizing a first order before cutting.
Worldwide Shipping
XTRA Motorsport ships M22759/32 Tefzel wire globally via DHL or UPS. Wire is cut to order and dispatched within 1–2 business days.
| Region | Carrier | Transit |
|---|---|---|
| Europe (EU, UK, CH, NO) | DHL Express / UPS | 1–3 business days |
| United States & Canada | DHL Express | 3–5 business days |
| Australia & New Zealand | DHL Express | 4–6 business days |
| Japan & Asia Pacific | DHL Express | 3–5 business days |
| Rest of world | DHL Express | 4–7 business days |
M22759/32 Tefzel wire is used by wiring harness builders across the US (IMSA, NASA, SCCA, time attack), Australia (Supercars, WTAC), and internationally for GT3/GT4 OEM programmes. All wire ships with a batch certificate of conformance to SAE AS22759/32 on request.
FAQ
What is the difference between M22759/32 and Spec55?
M22759/32 is the mil-spec designation (SAE AS22759/32). Spec55 is the Raychem/TE Connectivity brand name for wire manufactured to the same specification. The part number series 55A0111 (Spec55) and M22759/32 are functionally identical for motorsport use. However, “Spec55” is also used informally to refer to M22759/44 — the 200°C silver-plated variant. XTRA Motorsport stocks M22759/32 (tin-plated, 150°C). If you need the 200°C silver variant, specify M22759/44 or M22759/33.
What is the difference between M22759/32 and M22759/44 — which should I use?
M22759/32 uses tin-plated copper and is rated to 150°C. M22759/44 uses silver-plated high-strength copper and is rated to 200°C. Both use the same thin 0.005 in ETFE wall, so OD and weight are nearly identical. For the vast majority of ECU harness circuits — sensors, injectors, I/O, power distribution — M22759/32 at 150°C is sufficient, provided the harness is routed away from direct exhaust heat. Use M22759/44 only for circuits that must route through sustained high-temperature zones (exhaust tunnel, turbo outlet area).
Is Tefzel wire the same as PTFE wire?
No. Tefzel is the DuPont brand name for ETFE (ethylene tetrafluoroethylene), which is a different polymer to PTFE (polytetrafluoroethylene, also called Teflon). For motorsport, cross-linked modified ETFE (M22759/32) is preferred over PTFE because it has higher tensile strength (38–48 MPa vs 13–25 MPa for PTFE), better abrasion resistance, and is significantly lighter.
What temperature can M22759/32 wire handle?
Continuous rated temperature is 150°C (−65°C to +150°C). The insulation passes an ageing test at 300°C for 7 hours without failure — this is a production verification test, not a continuous operating limit. For circuits requiring 200°C continuous rating, use M22759/44 (silver-plated conductor, identical wall profile).
Can I use M22759/32 with factory OEM rubber wire seals?
The thin ETFE wall gives M22759/32 a smaller OD than most OEM wire seal bores — at 22 AWG, OD is 1.04–1.14 mm vs a typical OEM seal bore of ~1.3–1.5 mm. A short sleeve of Raychem SCL heat shrink over the seal zone builds OD to fit. For dedicated motorsport connectors (Autosport, ASL, ASU, Souriau 8STA, Deutsch DT/AS/DTP), M22759/32 is the correct wire and fits without modification. If OEM seal compatibility is a priority throughout, consider M22759/16 instead, which has a thicker wall and larger OD closer to OEM seal sizing.
Can I use standard automotive wire strippers on Tefzel wire?
Standard blade strippers are not recommended. The thin ETFE wall (0.005 in) and 19-strand construction require precision strippers with a blade gap matched to the wire gauge. Incorrect stripping nicks the tin-plated strands and reduces pull-out strength at crimp terminations. The correct tool is the Ideal Ergo-Elite Stripmaster (part 55-1987) for 16–26 AWG M22759 wire.
How much weight does M22759/32 save compared to TXL wire?
At 22 AWG, M22759/32 weighs 4.2 g/m versus TXL at approximately 5.95 g/m — approximately 29% lighter. For a 200-circuit harness with an average 1.5 m per circuit, the weight saving over TXL is approximately 500 g. At 20 AWG the saving is approximately 17%. The combination of thinner OD and lower weight makes M22759/32 the standard choice for any build where harness mass is a design parameter.
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