Trailer locks, explained simply
Find the right lock for your coupler, hitch, wheels and doors. We compare manufacturer specs, fit charts, materials, list prices and owner reports so you can buy once and buy right. Every guide says when it was last checked and links to the maker pages we used.
Find your lock by trailer type
| Trailer | Main risk | What to buy first | Guide |
|---|---|---|---|
| Utility or landscape trailer | Hitched to another truck from the driveway in under a minute | Coupler lock sized to your ball (often 2 in) | Best coupler locks |
| Boat trailer | Taken from the ramp lot or winter storage; salt corrosion | Corrosion-resistant coupler lock (surge-brake fit), wheel lock for storage | Boat trailer locks |
| Travel trailer or RV (bumper pull) | Campground and storage-yard theft | Custom-fit 2-5/16 in coupler lock plus hitch pin lock | Coupler locks, hitch locks |
| Enclosed or cargo trailer | Break-in for tools and equipment | Shrouded door lock and a coupler lock | Door locks |
| Gooseneck, horse or stock trailer | High-value rig, brand-specific coupler | Gooseneck lock made for your coupler brand | Gooseneck locks |
| Any trailer in long storage | Determined thieves with time | Wheel lock or boot as a second layer | Wheel locks |
| Heavy-duty work trailer | Class IV/V hitch, heavy loads | Rated 5/8 in locking pin with the right span | Heavy-duty hitch locks |
Choosing between premium brands
Proven Industries and AMPLock are the two custom-fit brands owners ask about most. They differ in design, lock core, warranty and which couplers they fit. Our AMPLock vs Proven comparison puts the maker specs and list prices side by side with links to every source.
All guides
Find your size
The ball size is stamped on the coupler: 1-7/8 in, 2 in or 2-5/16 in. Most boat and light utility trailers use 2 in; most travel trailers and larger utility trailers use 2-5/16 in. Receiver hitch pins are usually 1/2 in for 1-1/4 in receivers and 5/8 in for 2 in and larger. Measure the usable span of the pin as well as its diameter; our hitch pin sizing guide shows how.
Layer your locks
No single lock stops a thief with a battery grinder and time. Most trailer theft is quick and opportunistic, so the goal is to make your trailer slower and more visible to steal than the one next to it. A good layered setup is a coupler lock whenever the trailer is unhitched, a hitch pin lock and latch lock when it is hitched and parked, and a wheel lock for multi-day storage. Buying from one brand often lets you key them alike, so a single key opens everything. Park with the tongue against a wall where you can, keep photos of the VIN plate and serial numbers, and consider a hidden GPS tracker for valuable trailers.
How we research
We compare manufacturer specs, fit charts, materials and owner reports, and show prices as list prices or approximate ranges from maker sites. We have not lab-tested these locks and we do not invent ratings or test results. Read more about our method.