How to Determine Square and Round Tube Axle Capacity
Question:
Does the weight chart also apply to square axles? I have like a 4inch square axle and Im now sure its weight capacity...
asked by: Brandi
Expert Reply:
Looks like you found the chart that Jeff D made that shows common axle capacities based on diameter:
Typical Axle Diameters Based on Axle Capacity
- 1,000-lb - 2,000-lb Axles: 1-1/2 inch - 1-3/4 inch diameter
- 3,500-lb Axles: 2-3/8 inch diameter
- 6,000-lb - 7,200-lb Axles: 3 inch diameter
- 8,000-lb Axles: 3-1/2 inch diameter
- 9,000-lb Axles: 4 inch diameter
- 10,000-lb Or more axles: 5 inch diameter
These capacities are for round axles.
Square axle capacities are pretty hard to determine. Unlike round axles, they do not have set capacities based on their dimensions. But what you can do is give me some exact measurements of your spindle and/or the bearing numbers of the hub you have and we should be able to see if there is a hub we carry that would fit so that you could at least get a ballpark on your capacity.
I need the dimensions of where the bearings and seal ride.

Product Page this Question was Asked From
Dexter Trailer Idler Hub Assembly for 6,000-lb Axles - 6 on 5-1/2
- Trailer Hubs and Drums
- Hub
- Standard
- 25580 / 15123
- Standard Grade
- For 6000 lbs Axles
- 1/2 Inch Stud
- 6 on 5-1/2 Inch
- 16 Inch Wheel
- 16-1/2 Inch Wheel
- 17 Inch Wheel
- 17-1/2 Inch Wheel
- 18 Inch Wheel
- 18-1/2 Inch Wheel
- Dexter
more information >
Continue Researching
- Article: How to Tell the Weight Rating of a Trailer Axle
- Video: Hands-On with the etrailer Hub Bearing Kit
- Video: Review of etrailer Trailer Bearings Races Seals Caps - Hub Bearing Kit 3500LB Axle - BK2-100
- Search Results: wench
- Shop: Trailer Axle with Idler Hubs - 5 on 4-1/2 Bolt Pattern - 95" Long - 3,500 lbs
- Shop: CE Smith Winch Stand - Galvanized Steel - 30" Tall x 2" Wide
- Shop: Single-Speed Boat Trailer Winch with 20' Strap - 1,800 lbs
- Q&A: Tips for Determining Square Trailer Axle Capacity
- Shop: 4-Leaf Slipper Spring w/ Open Eye End for 4,300-lb Trailer Axles - 26-1/4" Long
- Shop: 3-Leaf Double-Eye Spring for 4,000-lb Trailer Axles - 25-1/4" Long
- Shop: 4-Leaf Slipper Spring w/ Radius End for 2,000-lb Trailer Axles - 24-5/8" Long
- Video: Let’s Check Out the 4-Leaf Slipper Spring w/ Open Eye End for 4,300-lb Trailer Axles
- Shop: Kenda Karrier KR53 ST205/75R15 Radial Trailer Tire with 15" Silver Mod Wheel - 5 on 4-1/2
- Q&A: Comparing Chinese Bearings with Bearings Made in the USA
- Q&A: How to Tell if Trailer has a BT8 or BTR Spindle Installed
- Q&A: Trailer Axle Weight Rating for 2 Inch Square Axle
- Shop: Trailer Hitch
- Q&A: How to Determine Correct Replacement Slipper Springs
- Article: How to Measure Your Trailer Wheel Bolt Pattern
- Search Results: 3500 lb spindle
- Search Results: slipper springs
- Search Results: axle grease caps
- Search Results: 28 leaf spring
- Search Results: 28 inch leaf springs
- Article: Printable Trailer Bolt Hole Pattern Template
- Search Results: tie down anchors
- Q&A: Replacement Bearing And Seals For UFP Hub H-1062-2
- Video: Optronics Trailer Lights A16RB Review
- Article: How to Raise Your Travel Trailer Height
- Q&A: Can Shackle Straps Be Used On Both Sides Of The Leaf Springs