Can You Reuse Wheels When Upgrading from 7K to 8K Trailer Axles?
Posted by Kaleb Carter on Apr 30th 2025
Thinking about swapping your 7K axles for 8Ks? One of the most common questions we get from customers is:
“Do I have to change my wheels too?”
Not necessarily — but we recommend paying close attention to your tire rating to make sure your setup is properly rated for the increased axle capacity. Yes, the bolt pattern is the same for 7K and 8K axles, but the load rating and components matter if you're trying to do it right.
Same Bolt Pattern – But Load Rating Still Matters
Both 7K and 8K axles use the 8-lug on 6.5” bolt pattern, meaning you can reuse your 16” or 17.5” wheels on either axle.
However, it’s a good idea to check the following:
- Your tires are rated to handle the load
- You’re using the correct lug nuts for your wheel style
Just because it fits doesn’t mean it’s suited for the weight you're carrying.
Tire & Wheel Load Ratings — What You Need to Know
Even if the bolt pattern fits, pay attention to your tire load rating. If your tires can’t handle the weight, upgrading the axle becomes pointless — your trailer will still be rated at the lower component.
? Load Chart for 7K & 8K Axles
| Tire Size | Load Range / Ply | Rating Per Tire | Notes |
|---|---|---|---|
| 235/80R16 | E / 10-ply | ~3,520 lbs | ✔️ OK for 7K, ❌ Too low for 8K |
| 235/80R16 | G / 14-ply | ~4,000–4,400 lbs | ✔️ Works for 8K |
| 235/85R16 | H / 16-ply | ~4,540 lbs | ✔️ Good match for 8K |
| 215/75R17.5 | H / 16-ply | 4,805 lbs | ✔️ Ideal setup for 8K trailers |
| 235/75R17.5 | J / 18-ply | 6,005 lbs | ✔️ Overbuilt option for commercial use |
Example: If you’re running 10-ply tires (3,520 lbs rating), you’re still limited to ~7,040 lbs per axle — even if your axles are rated for 8K.
Stud Size – Only a Concern for 7K Axles
Carter 8K axles come standard with:
- 5/8” studs
- Swivel flange lug nuts (best match for 17.5” wheels)
If you’re using 16” wheels, just let us know — we’ll include:
- 5/8” cone-style lug nuts to match your wheel type
There’s no need to check stud size on 8K axles — they’re always 9/16” or 5/8”.
When stud size does matter:
If you’re putting 17.5” wheels on a 7K axle, check this:
| Stud Size (7K Axles) | 17.5” Wheel Safe? | Notes |
|---|---|---|
| 1/2” | ❌ Not recommended | Risk of broken studs |
| 9/16” or 5/8” | ✔️ Yes | Matches heavier wheel & tire |
Final Thoughts
You don’t have to change your wheels when upgrading from 7K to 8K axles — but it’s smart to review your tire load rating, stud size (if running 17.5” on a 7K), and make sure the lug nuts match the wheels.
It’s all about keeping the setup strong, safe, and reliable — not just “fitting” it together.