How To Measure Your Trailer's Wheel Bolt Circle Lug Or Bolt Pattern

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advice, boat trailer, safety, tips - January 23, 2017

How to Measure your Trailer's Wheel Bolt Circle Lug or Bolt Pattern

In order to replace a hub on your trailer, you will need to know the bolt pattern or lug pattern. Trailer wheel hub patterns can be defined by the number of bolts or lugs per wheel and the diameter of the circle that the bolts are arranged on.  Determining the bolt pattern is rather easy, but it is very important that accurate measurements are taken.  The majority of boat trailers on the road have a 4, 5 or 6 lug pattern. A very common designation for boat trailer hubs would be 5 on 4-1/2 or 545 for short.  This means that the hub has 5 bolts spaced evenly on a 4-1/2" circle (see 5-lug diagram).

Determining the bolt pattern on your trailer:

1. You will need to first count the number of lug bolts on one wheel. Most trailer hubs typically have 4 or 5 lugs per wheel/hub. Heavier duty, higher capacity trailers generally have 6 or 8 Lugs per wheel.
2. If the trailer hubs have an even number of bolts holding the wheel, measure from the center of one bolt to the center of the bolt directly opposite using a ruler, tape measure or caliper.  The hub lug bolt pattern will be determined by the number of lug bolts and the distance between the opposing hub bolt (see 4-lug hub diagram).  All but 5-lug patterns are measured in this manner. 
3. If your trailer wheel hubs have 5 lug bolts, measuring is slightly different. Choose any lug bolt and measure the distance between the back of one lug to the center of another that is directly across from it. Be sure that you skip one bolt when measuring.  You can measure the distance in either direction

The two most common lug patterns are 4 on 4" and  5 on 4-1/2" hubs. These hubs are typically seen on smaller boat and utility trailers.  NOTE:  If you are replacing older wheel hubs, wheels, integrated hub/drums or hub/rotors the bearings should be checked for wear and replaced as necessary. Always use a high-temperature wheel bearing grease when re-packing your trailers hubs. 4, 6 and 8 Lug trailer wheel hubs are all measured in the same manner. If you need to replace your hubs, please see our current selection of boat trailer hubs. We also have a full selection of grease & oil and bearings & seals for all your needs. Share Share on Facebook Tweet on Twitter Pin on Pinterest

20 comments

• Robert Kukla December 8, 2023

  I have an older trailer that takes a 4 log pattern.Where can I find one?Need 2 of them.

• Donald December 8, 2023

  I have a 5×8 enclosed trailer , wheels &tires lean toward on both sides the the old beetle Volkswagen did and it’s wearing my tires out on the out side each side , any ideas here thanks

• David Reyna December 8, 2023

  My 5 lug wheels measure 5" from outside to center of lugs. Is that common on my tandem trailer?

• Miguel Briones January 27, 2021

  Hi, why would the rear wheels on my tandem axel trailer would be wearing out all choppy, is there any adjustment I need to make or do I have to use radial tires?

• Michael May 11, 2020

  I bought a hub bearing kit from big Tex store and he put a template over the lugs and got to kits why is the axel nut to big I had to use my old washer and nut what’s the deal

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