I've run the same Train Horn for Milwaukee® 18v Battery in a fourth-gen Tacoma, a 2022+ Tundra CrewMax, and a 4Runner this year, and none of them saw a drill bit, an air line, or a wire. The Toyota forums are full of threads about where to hide a compressor and a tank; here's what it looks like when you don't have to.
Why Toyota Owners End Up Under the Truck With an Air-Tank Kit
Read the Tacoma horn threads and one line repeats: most people put the tank where the spare tire is. The bolt-in kits use a bracket in the spare-tire location under the bed — no drilling, which sounds great until your spare is riding in the bed or staying home. One documented 2016 Tacoma install used a 5-gallon, 20-pound tank plus an 11-pound compressor at 150 PSI for 10 to 12 seconds of horn per fill. That's over 30 pounds of hardware under a mid-size truck before the trumpets go on.
Tundra owners do the same dance one size up. A 2024 hybrid Tundra build on Tundras.com hung a 2-gallon tank off the frame near the spare, tucked a twin compressor on the driver's side, and pointed the horns down inside the fender well. It took custom brackets, 8-gauge power runs, a 4-gauge feed off the hybrid battery with a 60-amp breaker, and a fight with the inner fender liner tabs the owner called the biggest pain of the job. On the 4Runner, the popular fifth-gen under-hood compressor bracket takes 2 to 3 hours and, as one commenter found out, won't fit a 4Runner sold in California because of the extra emissions hardware on the passenger side. I'm in Kern County. I've been on the wrong end of that surprise.
A train horn for the Milwaukee® 18v battery skips all of it. Compressor, valve, receiver, and four trumpets are one unit that snaps onto an M18™ pack. Nothing gets plumbed, relayed, or bracketed into the Toyota. So "fit" stops being about frame real estate and becomes a question of where the horn rides in each vehicle — and that does change between a Tacoma, a Tundra, and a 4Runner.
Toyota Tacoma (2016–2026): Small Bed, Big Deck Rail
The fourth-gen Tacoma (2024 and up) comes with a 5-foot bed at 60.3 inches of floor or a 6-foot bed at 73.5 inches; the XtraCab only gets the 6-footer. Both run 44.7 inches between the wheel wells and 20 to 21 inches deep. The third gen (2016–2023) is narrower between the wells at 41.5 inches and shallower at 19.1. All of them swallow the horn with the battery on and keep it below the rail line.
What makes the Tacoma the easiest of the three is the factory deck rail system: sliding twist-lock cleats rated at 110 pounds each, up to three per side on the short bed and four on the long bed. That's a strap anchor wherever you want it, which is exactly what a bracketless horn needs. On a 2024 Double Cab short bed:
- Front passenger-side corner, cleat directly above it, trumpets aimed at the tailgate. One cam strap through the cleat and around the horn body. The bulkhead and wheel well box it in so it can't walk on washboard. My daily setting.
- Cleat slid to mid-bed, horn strapped to the rail, trumpets over the side. This is the loud setting. The trumpets clear the bed wall and the sound goes out sideways instead of into the tailgate skin.
- Behind the rear seat on a Double Cab. Grab it, drop the window, fire it, put it back.
If you've got a rack over the bed, I covered the height and clearance rules in my bed rack and roof rack mounting guide — a Tacoma with a mid-height rack puts the trumpets right where I want them.
Toyota Tundra (2022+): Three Beds, Same Answer
The third-gen Tundra is full-size, so the numbers grow: the 5.5-foot bed is 65.6 inches of floor (CrewMax only), the 6.5-foot bed is 77.6 inches, and the 8.1-foot bed is 96.5 inches (Double Cab only). All of them run about 48.5 inches between the wheel wells and roughly 20.9 inches deep, with the same composite floor and deck-rail-and-cleat system as the Tacoma. Everything I said about cleats applies word for word.
Two things differ. First, there's so much floor that the horn disappears in a corner; on the CrewMax 5.5 I strap it to the front driver-side cleat and it takes less room than a 5-gallon bucket. Second, firing from the floor with the tailgate up throws the sound mostly upward, so for events I lift it to the rail or set it on the open tailgate, trumpets out. The tank-kit crowd aims their horns down out of the fender well for the same reason.
Tundra owners who wire a tank system in tap a 40-amp relay off the factory horn wire or pull power straight from the battery. With the M18-compatible horn the trigger is a wireless remote, so the factory horn circuit never gets touched. On a hybrid Tundra that also means you're not splicing anything near a high-voltage system, which I'm happy to leave alone.
The Tundra mounts the same way any other half-ton does; the Ford, Chevy, and RAM versions are in my F-150, Silverado, and RAM 1500 fit guide.
Toyota 4Runner (5th and 6th Gen): The Roll-Down Rear Window Is the Trick
The 4Runner has no bed, and the engine bay is the one place I don't want an M18™ pack sitting all day. The good news: it has the best cargo-area horn setup of any SUV I've worked on, because of the rear window.
A sixth-gen (2025+) two-row gas 4Runner has 48.4 cubic feet behind the second row; the hybrid lands at 42.6 and the three-row gas model at 44.8. The fifth gen (2010–2024) had 47.2. Both generations keep the power roll-down rear window, and that's the whole install: strap the horn to a rear cargo tie-down with the trumpets facing the glass, drop the window from the driver's seat, fire it, roll it up. No drilling, no muffled blast, and the horn is out of sight with the window closed.
On the hybrid the cargo floor sits higher, so check that the trumpet mouths clear the window opening once the horn is strapped down. If you run a cargo drawer system, the horn rides on the drawer deck the same way; just strap it to a real anchor, not the drawer lid.
Which Horn Fits All Three Toyotas
I run the Extreme Quad Train Horn for Milwaukee® 18v Battery in all three vehicles. It's rated at 150 dB with four powder-coated metal trumpets, ships with a standard remote good to about 160 feet plus a long-range remote rated up to 2,000 feet, and runs on any Milwaukee® M18™ pack — battery sold separately, which is fine if you already have three on the charger. It's water-resistant, not waterproof, so it rides in the bed or cargo area rather than under the truck in tire spray.
The Dual at 130 dB and the standard Quad at 140 dB mount in the exact same spots. Pick the tier by what your neighborhood tolerates, not by which truck you drive.
| Vehicle | Where I put it | Anchor | Best firing position |
|---|---|---|---|
| Tacoma 5-ft / 6-ft bed | Front passenger-side bed corner | Deck rail cleat + cam strap | Strapped to the rail, trumpets over the side |
| Tundra CrewMax / Double Cab | Front driver-side bed corner | Deck rail cleat + cam strap | On the open tailgate or at rail height |
| 4Runner 5th / 6th gen | Cargo floor, trumpets at rear glass | Rear cargo tie-down | Rear window rolled down |
My 15-Minute Toyota Setup
- Dry-fit with the battery on. The pack adds length and changes the balance.
- Strap to metal, not trim. Deck rail cleats on the trucks, the cargo tie-downs on the 4Runner. Never the plastic bed-side pockets or a cargo-cover bracket.
- Aim the trumpets into open air. Tailgate down, window down, or trumpets above the rail. Pointing them into a bed wall throws away decibels.
- Keep the pack higher than the trumpets and reachable. Spray runs downhill, and you want to swap batteries without tools.
- Ear protection before the first test. NIOSH puts the recommended exposure limit at 85 dBA over an eight-hour shift and halves the safe time for every 3 dBA over that. A horn rated at 150 dB is not a bare-eared test, even in a Tundra bed.
If you'd rather skip straps, the magnet and clamp options in my no-drill mounting guide work here too — just remember the fourth-gen Tacoma and third-gen Tundra beds are composite, so a magnet has to grab the steel rail, not the floor.
FAQ
Do I lose my spare tire like the tank kits?
No. Nothing goes under the truck, so the spare stays where Toyota put it. That's the single biggest reason Tacoma owners ask me about a battery horn.
Will it fit a third-gen Tacoma or a fifth-gen 4Runner, or only the new ones?
Any of them. The horn was sized to an M18™ pack, not a vehicle. The older Tacoma bed is a few inches narrower and the older 4Runner has about a cubic foot less cargo room; neither changes where the horn goes.
Can I wire it to the steering-wheel horn button?
Out of the box it's remote-triggered, which is why it fits a hybrid Tundra with no splicing. What tying into the factory circuit would involve is in my factory horn button article, but on a Toyota I'd leave it wireless.
Is it legal to run this on the street in a Toyota?
Depends on your state. Off-road and private property are the easy case; on public roads most states limit horn use to real warnings. I keep a California guide and a state-by-state guide updated — read yours before you lean on the button in town.
Tacoma, Tundra, 4Runner: all three "fit" this horn because the horn was never asked to fit a Toyota. It fits the battery you already own. Loud is a feature — install it right. — Cole
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