There are 4 critical measurements when it comes to replacing a wheel. These are the wheel diameter, wheel width, hub length, and bore diameter. Other dimensions will be discussed as well, but are primarily shown for clarification.
The wheel diameter is the distance measured across
the side of the wheel. Occasionally the wheel will have its diameter and
width stamped or molded into the wheel itself, so take minute to check
and see if that is the case. If not, simply measure across the wheel.
Bear in mind that wear can cause up to ½” of material loss, so if your
current wheels are particularly worn you may need to round up to the
nearest half inch. Because there are very standardized wheel sizes, this
measurement can typically be taken with just a tape measure.
The bore diameter is the internal size of the bore.
This measurement is required in order for the wheel to fit the existing
axle assembly properly. While looking at the side of the wheel, measure
across the inside of the opening in the center of the wheel where the
axle passes through. This tends to be a more precise measurement than
the wheel diameter. If you have a micrometer or caliper, that would be
the preferred method of measuring. Another method would be to insert
drill bits until you found one that matched the size of the bore.
Wheel width is the widest part of the tread
material. This measurement is not nearly as critical as the hub length,
but is very helpful for locating the same or similar wheels. Generally a
tape measure will suffice for this measurement.
The last primary measurement is the hub length. This
is the distance between each side of the wheel through the bore. Proper
hub length allows the wheel to fit between the caster fork assembly
with minimal play. This measurement is more important than wheel width,
because it determines if the wheel will fit the frame or not. The wheel
width does not determine if the wheel will fit in the fork. A tape
measure will not typically fit through the bore to take this
measurement. Instead, use a piece of dowel or pencil and insert it
through the bore. Hold one end of the dowel flush with one side of the
bore, and mark the other side. Then you can remove the dowel and measure
from the flush end to the mark.
You will notice Hub Diameter and Tread Width on the images above.
These are shown for reference and to reduce confusion. Note that the
tread width is actually smaller in many cases than the wheel width.
With these measurements, you will be able find a replacement wheel.
Remember, if you have any issues or need further assistance, we’re here
to help. Give us a call at 1-800-215-8220.