The Question We Hear All the Time

“I’ve got a 7K axle with an 80‑inch spring center. Can’t I just swap it for a 10K or 12K axle?”

At first glance, upgrading seems easy—take out your 6K, 7K or 8K axle and bolt in a beefier 10K or 12K axle. But because of how axles are designed, it isn’t as straightforward as it sounds.

Understanding Hub Face and Spring Center

Two measurements decide whether an axle fits:

• Hub Face (HF): The distance from one wheel-mounting surface to the other—the overall width of the axle.

• Spring Center (SC): The distance between the mounting points where your leaf springs attach to the frame.

A larger axle needs more room between these points for bigger hubs and brakes. Smaller axles have less room.

Why the Spacing Matters

• 7K axles usually need about 15 inches of space per side between the hub face and spring center.

• 8K axles need about 17 inches of space per side.

• 10K or 12K axles need roughly 28 inches per side—almost twice as much as a 7K.

So upgrading from a 7K to a 10K isn’t just a bolt‑on job. To fit that bigger axle under your existing frame, you’d have to push the wheels way out—past the fenders and probably past the legal road width. Cutting off your old brackets and welding new ones farther inboard is possible, but it means major frame work and a whole new suspension.

Before You Grab a Welder

If you’re thinking about upgrading:

• Measure carefully. Going from a 7K to a 10K axle requires about 26 inches more clearance in total—13 inches on each side.

• Know the work involved. You might need to install new hangers and crossmember supports to make the wider axle fit.

• Ask yourself why. For most trailers with an 80‑inch spring center, the practical upgrade is to step up to an 8K axle, which fits without changing the frame and still gives you more capacity.

The Realistic Upgrade Path

For an 80‑inch spring center, moving to an 8K axle makes sense. Trailer Parts Unlimited sells 8K axles with a 97‑inch hub face and an 80‑inch spring center—so you keep the same frame width, stay within legal limits, and get a stronger axle. If you need 10K or 12K capacity, it’s usually best to buy a trailer built for it from the ground up.

Need Help?

We carry 7K, 8K, 10K and 12K axles along with the parts you need for safe upgrades. Call us at 844‑898‑8687, stop by Exit 118 in Huntsville, TX, or visit TrailerPartsUnlimited.com for advice.