Do You Need a Spare Tire Delete for a Train Horn? Why a Train Horn for Milwaukee® 18v Battery Keeps Your Spare

I get this question every time someone shops a train horn for a lifted truck: "Do I have to do a spare tire delete?" I've done two of those installs for customers, and I've bolted a Train Horn for Milwaukee® 18v Battery onto every rig I own without touching a spare. Here is what the spare tire delete actually is, why compressor kits push you toward it, and why a tankless horn on an M18™ pack sidesteps the whole problem.

The Short Answer: No Delete Needed, Because There Is No Tank

A spare tire delete exists for one reason. A conventional train horn kit needs an air tank and a compressor, and on a pickup the roomiest hidden space under the truck is the spot where the factory spare hangs. So the kit makers built brackets that winch up into the spare well on the factory crank, and the spare goes somewhere else or goes away.

The train horn for the Milwaukee® 18v battery has no tank. The compressor sits inside the horn housing and feeds the trumpets directly while you hold the trigger, so there is nothing 27 inches long to hide under the bed. The whole unit weighs 4.0 pounds before the battery. That is the entire answer: you keep your spare because there is nothing competing for its space.

What a Spare Tire Delete Actually Involves

I want to be fair to the tank-kit crowd, because the brackets themselves are well made. Here is what I found on the two most common spare-well systems versus the tankless horn I run.

The HornBlasters kit "will arrive as individual components and assembly will be required," and it is rated to fit most full-size pickups and SUVs. Kleinn's page is blunter, printing in capitals that the kit requires removal of the spare from its stock location under the bed. Neither company is hiding anything. They are telling you up front that the spare is the price of admission.

One frame-mount install guide I read pegs a Tacoma spare well at roughly 28 by 20 by 8 inches, good for a 2 to 2.5 gallon tank, and a full-size well at about 32 by 28 by 10 inches for 3 to 5 gallons. That same guide budgets 4 to 5 hours of DIY time on a Tacoma and 5 to 6 on a full-size pickup, and its advice on the spare is to move it to the bed or a trailer, or skip it entirely on a daily driver. I have heard that last option a hundred times, and it is the part I push back on.

Why I Keep My Spare

Nobody is going to arrest you for running without a spare. The federal tire standard, FMVSS 110, does not require one at all. It only says that if no spare is provided, the word "none" must replace the tire size on the door placard, which you can read yourself in 49 CFR 571.110, section S4.3. Plenty of new cars ship with an inflator kit and no spare. Legal is not the question. Practical is.

Here is my practical. I run 35s on my off-road truck in Kern County, where the nearest tire shop from the trailhead can be an hour of washboard away. A plug kit fixes a nail in the tread. It does not fix a sidewall gash from a rock, and a rock is what you hit out there. A full-size spare on a matching wheel is the only fix for that, and it does not fit in the bed with a side-by-side loaded, which is why the factory hung it under the truck in the first place.

The delete guides tell you to relocate the spare to the bed or a bumper carrier. Both work. Both also cost bed space, or a swing-out bumper you now have to buy and install. So a "no drill" bracket that saves you fabrication ends up costing you a spare relocation project on the other end. When I add up the real bill for a tank kit, that swing-out carrier is a line item most people forget, which is why I broke the numbers down separately in my train horn cost comparison.

Where the Horn Lives Instead

With nothing to hide under the frame, the question flips from "where do I fit a tank" to "where do I want the trumpets pointing." On my daily truck the horn rides on the bed rack with the trumpets aimed forward over the cab. On the trail rig it is clamped to the roll bar of the side-by-side, and the same horn rides home on the boat in summer. I've covered every one of those setups in my no-drill mounting guide, with straps, magnets, and clamps rated for the load.

The horn I run for this is the Extreme Quad Train Horn for Milwaukee® 18v Battery. It is rated at 150 dB, carries four powder-coated metal trumpets in four sizes, and ships with a standard remote rated to 160 feet plus a long-range remote rated to 2,000 feet. Snap on any Milwaukee® M18™ pack and it is armed. Pull the pack when you are done for the day, because the maker's own guidance is to disconnect the battery if the horn will sit unused for more than about five hours.

Shop the Extreme Quad Train Horn for Milwaukee® 18v Battery →

The weight math is what sells people once they see it. The 5-gallon spare-well kit is 57 pounds hanging behind your rear axle, plus a spare relocated somewhere it was never designed to be. The tankless horn is 4.0 pounds, plus 1.8 pounds for a Milwaukee® M18™ XC5.0 pack, and the spare stays exactly where the factory engineers put it. If you want the horn out of sight, the smaller footprint also opens up spots a tank could never use. I listed my favorites in the hidden and stealth mounting guide.

There is a warranty angle too. A spare-well kit means a fused 12V feed, a relay, and a pressure switch spliced into the truck. The battery horn touches none of your wiring, which is the whole argument in my piece on whether a train horn voids your truck warranty.

What You Give Up Without a Tank

I am not going to pretend the tank has no upside. The 5-gallon HornBlasters kit is rated for 10 to 12 seconds of honk per fill, and both brands sell the spare-well tank as onboard air for tires and small air tools. If airing up 37s at the end of a trail is the real reason you want a compressor under the truck, buy the compressor for that job and be honest that the horn is riding along.

For the horn itself, the tank is a liability, not a feature. Every blast drains it, and the 5-gallon kit needs about two minutes at 25 amps to climb back from 110 to 150 PSI. The battery horn has no tank to empty, so blast length is whatever you hold the trigger for, and the sound starts the instant you press. I laid out the full tradeoff in battery train horn vs air-tank kit, and the short version is that the tank only wins if you want compressed air for something other than noise.

Two more honest notes. The horn is water-resistant, not submersible, so it rides inside a cab or under a cover in real rain. And 150 dB is a hearing-damage number at close range. Wear plugs, aim the trumpets away from anyone, and keep it off public roads except for a genuine emergency. Loud is a feature. Install it right.

FAQ

Can I run a Train Horn for Milwaukee® 18v Battery and keep my full-size spare under the bed?

Yes. The horn has no tank or compressor to mount under the truck, so the spare, the winch, and the crank stay exactly as they left the factory. The horn mounts on a bed rack, a roll bar, or rides handheld.

Is it illegal to drive without a spare tire after a delete?

No federal standard requires a spare. FMVSS 110 only requires the placard to read "none" where the spare size would be if a vehicle ships without one. Check your own state's inspection rules, but in every state I have worked in, the spare is a judgment call, not a law.

Will the battery horn air up my tires like a spare-well tank kit?

No. The horn's compressor feeds the trumpets only. If you want onboard air for tires, that is a separate compressor purchase whether or not you own a horn.

How much lighter is the battery horn than a spare tire delete kit?

The horn is 4.0 pounds, plus 1.8 pounds for an XC5.0 pack. The HornBlasters Stealth kit is published at 50 pounds for the 2-gallon version and 57 pounds for the 5-gallon version, before the relocated spare.

Does the horn need any wiring into the truck?

None. Power comes from the M18™ pack clipped to the horn, and the wireless remote triggers it from up to 2,000 feet with the long-range remote. There is no relay, fuse tap, or pressure switch.

Keep your spare. Put the horn where you can reach it. — Cole

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