A flat on a trailer is one of those problems that arrives at the worst possible moment: loaded down, on a shoulder, miles from the shop. The fix is a good spare, a jack that reaches the axle, and a place to carry the tire that does not rattle loose on the first rough road. Choosing the right spare tire rack is a small decision that pays off big when you actually need it.
This article is based on original reporting and manufacturer specifications available at the time of publication.
Quick Comparison: Spare Tire Rack Types
| Rack Type | Best For | Mounting Location | Typical Cost |
|---|---|---|---|
| Bolt-on Tongue Mount | Utility & boat trailers | Trailer tongue | $40-$100 |
| Swing-Away Carrier | Enclosed cargo trailers | Rear door frame | $80-$200 |
| Under-Frame Mount | Flatbed & equipment trailers | Underside of frame rail | $60-$150 |
| Vertical A-Frame Mount | Travel trailers & RVs | A-frame near hitch | $70-$180 |
What Types of Spare Tire Racks Are Available for Trailers?
There are four main types of spare tire racks used on trailers: bolt-on tongue mounts, swing-away carriers, under-frame mounts, and vertical A-frame mounts. Each one is built for a different trailer style and load situation.
Bolt-On Tongue Mount
This is the simplest and most common option, especially on utility and boat trailers. It bolts directly to the trailer tongue and holds the spare in a vertical or near-vertical position. It is cheap, easy to install, and keeps the tire out of the way of cargo.
The tradeoff is limited clearance. On trailers with short tongues or tight turning setups, a tongue-mounted spare can interfere with the tow vehicle during sharp turns.
Swing-Away Carrier
Swing-away carriers are popular on enclosed cargo trailers because they mount to the rear door frame and pivot out of the way when you need to open the doors. These racks are sturdier and designed to carry larger, heavier spares without sagging over time.
They cost more than a basic tongue mount, but the added durability and functionality make them worth it for trailers that haul heavier loads.
Under-Frame Mount
Found mostly on flatbed and equipment trailers, under-frame mounts tuck the spare beneath the trailer bed. This keeps the deck clear for cargo and keeps the tire protected from the elements.
The downside is accessibility. Pulling a spare out from under a loaded flatbed on the side of the road, especially in mud or snow, is not fun. It also exposes the tire to more road debris and corrosion over time.
Vertical A-Frame Mount
Common on travel trailers and small RVs, this style mounts the spare upright near the hitch on the A-frame. It keeps the tire visible, easy to reach, and out of the cargo area entirely.
These mounts are built to handle the larger, heavier tires often used on travel trailers, and they usually include a locking mechanism since RV spares are a common theft target.
How Do You Choose the Right Fit for a Spare Tire Rack?
The right fit comes down to matching the rack’s weight rating, bolt pattern, and mounting surface to your specific trailer and tire. A rack that looks right but does not match these specs can fail exactly when you need it most.
Start with the weight rating. Every rack has a maximum load capacity, and it needs to exceed the actual weight of your spare tire and wheel combination, not just come close to it. A 15-inch trailer tire and wheel can weigh anywhere from 35 to 60 pounds depending on construction, so check your spare’s actual weight before buying.
Next, confirm the bolt pattern and hub size match your trailer’s existing wheels. Most racks are designed around standard patterns like 5-on-4.5 or 6-on-5.5, but mismatches happen more often than you would think, especially with trailers that have been repaired or modified over the years.
Finally, check the mounting surface. Tongue mounts need enough flat, unobstructed tongue length. Swing-away carriers need a solid door frame rated to handle the extra weight and leverage. Under-frame mounts need adequate ground clearance so the spare does not drag on uneven terrain or steep driveway approaches.
What Safety Checks Should You Run Before Hitting the Road?
Before any trip, run through three quick checks: tightness, tire condition, and rack security. These take less than five minutes and can prevent a bad situation from getting worse.
Check the Hardware Tightness
Vibration from the road loosens bolts and lug nuts over time, even on a spare that never touches the ground. Check the mounting bolts and any locking lug nuts at every oil change or at least once a season. A rack that rattles is a rack that is working its way loose.
Inspect the Spare Tire Itself
A spare that has not been checked in a year can be flat, dry-rotted, or cracked by the time you need it. Check air pressure monthly and look for sidewall cracking, which is common on trailer tires that sit exposed to sun and weather for long stretches. Most trailer tires should be replaced every 5 to 7 years regardless of tread depth, since the rubber degrades faster than the tread wears.
Confirm the Rack Is Rated for the Load
Double-check that the rack’s actual load rating, not just its listed capacity, still matches your tire and wheel setup, especially if you have swapped to a heavier spare since installing the rack. A rack rated for a 50-pound spare will not hold up long under a 65-pound wheel and tire combination, even if it looks secure at first glance.
Test for Movement
Give the mounted spare a firm shake by hand before any long trip. There should be zero play between the tire, the rack, and the mounting point. Any wobble means something is loose, worn, or incorrectly torqued, and it needs attention before you leave the driveway.
Bottom Line
A trailer spare tire rack is a small investment that solves a big problem on the road. Picking the right type for your trailer, matching the weight rating and bolt pattern correctly, and running quick safety checks before every trip keeps your spare ready when a flat actually happens. Skip these steps, and you risk discovering the hard way that your backup plan was never secure to begin with.
