This is a very common request we hear:
“I need a 74” spring center and around a 98” hub face.”
Sounds simple—but when you step into a 10K axle, the geometry doesn’t allow it.
The Rule Most People Don’t Know
On a 10K axle, you need a minimum of 26” difference between hub face and spring center.
- That equals 13” per side
- This spacing is required to properly fit:
- Larger 12-1/4” x 3-3/8” brakes
- Bigger hubs and drums
- Heavier spindle assemblies
There’s no way around this—it’s how these axles are built.
What Happens With a 74” Spring Center
If you have a 74” spring center, the shortest hub face you can realistically run on a 10K axle is about 100”.
So:
- Requested: 98” hub face
- Reality: ~100” minimum
That extra width matters more than people think.
Why This Becomes a Problem
This isn’t about fitment—it’s about legality.
Running a 100” hub face with a 74” spring center will push your setup over legal road width.
- Tires will stick out past the fenders
- You’ll be outside legal limits for highway use
- You’re opening yourself up to:
- DOT violations
- Fines
- Getting pulled over
If the trailer is off-road only, then it’s not a big deal.
But if you’re running on public roads, you’re taking a risk every time you tow it. If you’re willing to deal with the tickets and hassle, that’s on you—but you will be over width.
Simple Breakdown
- 74” spring center requires ~100” hub face on a 10K
- You cannot achieve 98” with that setup
- The result is a wider trailer that can put you outside legal limits
What Are Your Options?
If you’re trying to stay within a tighter width, here’s what actually works:
1. Stay with a lighter axle (7K or 8K)
Allows tighter hub face dimensions and is easier to match your current setup
2. Move your spring hangers
Adjusting hanger placement allows proper geometry for a 10K axle
3. Accept the wider setup
Only makes sense if the trailer won’t be used on public roads
Bottom Line
You can’t cheat axle geometry.
If you’re running a 74” spring center, a 98” hub face is not possible on a 10K axle. The required spacing forces you wider, and that can create real legal issues on the road.
Need Help Getting It Right?
We deal with this every day and can make sure you get the correct setup the first time—no guessing, no wasted money.
TrailerPartsUnlimited.com
844-898-8687
631 TX 75 N Huntsville TX 77320
Pick up in-store or have it shipped straight to you.