How to Measure?
We receive more inquiries regarding wheel weight mounting patterns than on any other subject. The major contributing factor to consumer confusion is the tendency of some manufacturers to state the mounting pattern (bolt pattern) in BCD (Bolt Circle Diameter) or the equivalent PCD (Pitch Circle Diameter) for the weight mounting holes on their wheels. They often state this specification and leave out the number of equally spaced mounting holes on the circle. Even if they provided both the PCD/BCD specification and the number of equally spaced mounting holes, this would have to be detailed in the wheel weight specifications as well. Note below how two wheels can have the exact same bolt circle or pitch circle diameter for mounting wheel weights but take very different types of wheel weights due to the number of equally spaced mounting holes.
Most wheel weights are described using the much simpler chordal method. The chord length method relies on the number of actual mounting holes and the distance between each mounting hole. Although this is the industry standard, confusion often arises in determining the correct number of mounting holes. In this blog, we are ONLY discussing the wheel weight mounting holes and NOT the holes used to mount the wheel to the tractor.
The vast majority of tractor wheel weights mount with either a 3-hole mounting pattern or a 4-hole mounting pattern. There are exceptions, but they are very rare. If your wheel simply has 3 mounting holes for the wheel weights or 4 mounting holes for the wheel weights, the mounting pattern is very simple. Measure from one mounting hole to the next mounting hole and that is your pattern. Say you have 3 equally spaced holes in your wheel and you measure 14” between one hole and the next hole, your mounting pattern would be 3@14”. If you had 4 equally spaced holes in your wheel and you measured between one hole and the next hole (like you were measuring one side of a square) and you come up with 11 ½ inches, your mounting pattern would be 4@11 ½”
If you have more holes in your wheel, remember, most weights mount with either a 3-hole or 4-hole pattern. If you have six equally spaced wheel weight mounting holes around your rim, you would have a 3-hole mounting pattern. To get your length, measure from the center of one hole, skip a hole, to the center of the next hole. A similar 8-hole wheel would be a 4-hole pattern and you would get your length by skipping a hole.
Sometimes wheels have more holes but they are not all equally spaced from each other. This is usually observed on wheels that have multiple hole patterns to accept different styles of wheel weights. A very common example is a wheel with 6 equally spaced holes (which will provide a 3-hole mounting pattern as described above) and 4 equally spaced holes which provides a 4-hole mounting pattern for a different style of wheel weight. The equally spaced pattern requirement is the key when measuring your wheel’s pattern.
It can be hard to get a center-to-center measurement with a tape measure where you are trying to eyeball the center of the mounting hole. See the pictures below for the easier method.
We get a lot (I mean a huge volume) of inquiries from people who have measured straight across their hole pattern without regard for the number of holes in the wheel. This happens even after we walk them through the correct process. Usually, we just ask them how many equally spaced holes are in the wheel and then convert their measurement for them so that we can be sure they are getting the right wheel weight. If this is how you measured your wheel, or if measuring that way is easier due to the shape of your wheel, please see the printable conversion instructions here.
If you are doing your own chordal length distance calculation, you may find our printable inch fraction to decimal conversion chart very handy.
View the Chart Here.
⚠ When Choosing and Installing Additional Ballast: ALWAYS refer to the recommendations contained in the owner’s manual for your equipment. ALWAYS refer to the maximum load rating of your tire .
Please keep in mind that many weights use the same mounting pattern but will not fit in all wheels that contain the same mounting pattern. The shape of your wheel and the shape of the wheel weight are also very important. Generally, when shopping for wheel weights, you need to know the diameter of your rim, the mounting hole pattern in the rim that is used to mount wheel weights, the load rating of your tires, the weight of your machine, and the shape of your wheel. We have a much more complete section on wheel weight mounting patterns that we encourage you to review. If you have any questions or concerns, please contact us.
This blog is general information only, representing the opinions of the author, and does not cover all aspects of the subject matter. Use of the information contained herein is voluntary.
