Trailer Hitch Classes
Towing & Hitches · 7 specs
Direct Answer
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.
Source: SAE International Standard J684_201405 (Trailer Couplings, Hitches, and Safety Chains — Automotive Type) · Last reviewed Aug 28, 2026
Specs
| Standardization | SAE J684 / VESC Regulation V-5 |
| 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 |
The 2.0-Inch Class III Universal Ecosystem
The Class III 2.0-inch (50.8 mm) square receiver is the most versatile automotive mounting port in North America: beyond towing heavy trailers, it supports an entire industry of hitch-mounted accessories, including 4-bike platform racks, swing-out tire carriers, cargo baskets, and winch mounts.