How to Find Wheel Bolt Pattern to Find the Correct Replacement Trailer Brakes

Question:

How do I measure bolt pattern for breaks on a 5 bolt rim.

asked by: George

Expert Reply:

There are a couple of methods you can use to determine bolt pattern of the wheels themselves. First, you can use the number of lugs and the bolt circle. For an even number of lugs, measure the center to center distance of 2 lugs directly across from each other. If you had 6 lugs and the distance measured is 5 inches, you have a 6 on 5 bolt pattern.

For an odd number of lugs, it is a little more difficult. Measure from the center of 1 lug directly across to the center point between 2 lugs on the other side. See the picture to the right for more clarification.

You can also use the center to center distance between bolts holes next to each other to determine bolt pattern.

2-5/8 inches - the bolt pattern is 5 on 4-1/2
2-3/4 inches - the bolt pattern is 5 on 4-3/4
3 inches - the bolt pattern is 5 on 5
3-1/4 inches - the bolt pattern is 5 on 5-1/2

I have included a link below to an FAQ article on determining bolt pattern.

To find the bolt pattern on the brake mounting flange on the axles, you will need to measure the distance between bolt holes. On a 4 bolt pattern, the holes are spaced 2-7/8 inches (4 on 2-7/8), like # 4-34. It works with 7 inch brake assemblies, 2,000 pound axles. It has a center hole inner diameter of 1.64 inches, and fits 1-3/4 inch round axles that use 1-1/4 and 1.38 inch round 2,000 pound spindles.

Another 4 on 2-7/8 flange is # 4-35. This flange is for use with 10 inch brake assemblies and has a center hole diameter of 2.27 inches.

Another common size is the 5 on 3-7/8 like # 4-44-1. This flange is for 12 inch brake assemblies. It fits 3 inch diameter axles rated at 4,400 and 6,000 pounds regular duty, 6,000 pound heavy duty, and 7,000 and 7,200 pounds.