How to Measure to Determine the Size Trailer Brakes Needed For Hydraulic Drum Replacement
Updated 09/04/2025 | Published 05/14/2017 >
Question:
Where does the measurement come from to determine if I have 2-1/4 or 2-1/2inch brakes? I need to replace the brakes on a Road King boat trailer with 3700# axles. It seems the wheel cylinder is blown out and rather than buying piece parts you kits seem to be the best option.
asked by: Chris
Helpful Expert Reply:
To determine the size of the brake assemblies you need you have to measure the depth and width of the hub drum on the axle like what you see in the picture I attached. The most common size is 2-1/4 inch wide like the # T4071600-500 that you referenced.

Joe C.
9/4/2025
10" x 2.5" - double axle can you give me a part number



Product Page this Question was Asked From
Dexter Hydraulic Trailer Brakes - Free Backing - 10" - Left/Right - 3,750 lbs
- Trailer Brakes
- Hydraulic Drum Brakes
- Standard Grade
- Free Backing
- Manual Adjust
- Single Servo
- 10 x 2-1/4 Inch Drum
- 3750 lbs Axle
- 14 Inch Wheel
- 14-1/2 Inch Wheel
- 15 Inch Wheel
- Dexter
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Matt O.
8/7/2020
12 x 2.5 drum trisaler brakes i just want the whole brake whitout botor i need probably 5