ISO 1724 (7-Pin) vs. Trailer Hitch Classes
Comparing 2 standards across 14 specifications. 14 key differences identified.
The ISO 1724 Connector (commonly known as the European Type 12N 7-Pin plug) is the classical European standard for basic trailer lighting. Featuring a circular 7-pin metal or plastic housing with split brass pins, it provides the essential exterior road lighting circuits (left/right turn, isolated left/right tail lights, brake lights, and rear fog lamp).
SAE J684 defines the standard classification system for passenger car and light truck receiver hitches in North America. It formally standardizes 4 classes (I–IV) based on receiver square tube opening dimensions (1-1/4", 2.0") and maximum Gross Trailer Weight Rating (GTWR from 2,000 lb up to 10,000 lb) and Tongue Weight (TW); a heavier-duty "Class V" tier is widely marketed by hitch manufacturers but is not itself an SAE J684-defined class.
Specification Comparison Table
14 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standardization
|
ISO 1724 / DIN 72577 (Type 12N–Normal) | SAE J684 / VESC Regulation V-5 |
|
Pin 1 (Yellow–Terminal L)
|
Left Hand Direction Indicator (Turn signal) | — |
|
Pin 2 (Blue–Terminal 54G)
|
Rear Fog Lamp (or +12V permanent feed on older caravans) | — |
|
Pin 3 (White–Terminal 31)
|
Common Chassis Ground Return | — |
|
Pin 4 (Green–Terminal R)
|
Right Hand Direction Indicator | — |
|
Pin 5 (Brown–Terminal 58R)
|
Right Hand Tail Light, Clearance Lights, and License Plate Lamp | — |
|
Pin 6 (Red–Terminal 54)
|
Brake / Stop Lights | — |
|
Pin 7 (Black–Terminal 58L)
|
Left Hand Tail Light and Left Hand Clearance Lights | — |
|
Class I (Light Duty)
|
— | Receiver: 1-1/4" (31.8 mm) square | Max GTWR: 2,000 lb (907 kg) | Max Tongue Weight: 200 lb (91 kg) — Compact cars and crossovers |
|
Class II (Medium Duty)
|
— | Receiver: 1-1/4" (31.8 mm) square | Max GTWR: 3,500 lb (1,588 kg) | Max Tongue Weight: 350 lb (159 kg) — Midsize sedans, minivans, small crossovers |
|
Class III (The Universal Standard)
|
— | Receiver: 2.0" (50.8 mm) square | SAE J684 baseline GTWR: 5,000 lb (2,268 kg); many commercially sold Class III hitches are manufacturer-rated higher (commonly 6,000–8,000 lb weight-carrying, more with weight distribution) | Max TW: ~500–800 lb — Full-size SUVs and pickup trucks. Actual capacity is always the figure stamped on the hitch itself, not the class name alone |
|
Class IV (Heavy Duty)
|
— | Receiver: 2.0" (50.8 mm) square | SAE J684 baseline GTWR: 10,000 lb (4,536 kg); some commercially sold Class IV hitches are manufacturer-rated up to 12,000–14,000 lb | Max TW: ~1,000–1,400 lb — 1/2-ton and 3/4-ton trucks towing heavy boat/travel trailers. Verify against the hitch's own rating label |
|
Class V (Commercial Extra Heavy)
|
— | Not an official SAE J684 class (SAE J684 formally defines only Classes I–IV) — "Class V" is an aftermarket-industry term for heavier-duty hitches, typically using 2" or 2-1/2" square receivers, marketed with GTWR ratings commonly in the 12,000–20,000+ lb range depending on manufacturer — Heavy duty commercial dually trucks |
|
Tongue Weight Safety Rule
|
— | Tongue weight must be 10% to 15% of total loaded trailer weight to prevent lethal high-speed trailer sway fishtailing |