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How To - Identify Orientation of Rims
How to identify if a passenger or commercial rim is a standard or "upside-down" rim.
How to identify if a passenger or commercial rim is a standard or "upside-down" rim.
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<p><strong>What to look for</strong></p><ul><li><p>Rims, both truck and car rim, have a short and long wellside.&nbsp;</p></li><li><p>The tyre needs to be pulled on and off the short side</p></li></ul><p></p>

What to look for

  • Rims, both truck and car rim, have a short and long wellside. 

  • The tyre needs to be pulled on and off the short side

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Step 2 of 7
<p><strong>The why</strong></p><p>While size designations for tires i.e., 245/40R<strong>18</strong> and wheels <strong>18</strong>x8 confirm matching <strong>18</strong>-inch bead seat diameters, measuring a wheel's overall diameter from the edge of one flange to the other, will reveal that the wheel, including its flanges, is actually about 1.4" larger (19.4-inches) than designated.<br>In order to mount a tire on a wheel, the tire's beads have to slide over a 7/10"-tall wheel flange on one side of the bead seat. Since the tire's steel bead wires don't stretch, this requires the wheel to also feature about a 7/10"-deep tire well/drop center around the wheel adjacent to the other side of the bead seat. This helps avoid damaging the tire's bead by allowing it to maintain its manufactured diameter when being mounted.</p>

The why

While size designations for tires i.e., 245/40R18 and wheels 18x8 confirm matching 18-inch bead seat diameters, measuring a wheel's overall diameter from the edge of one flange to the other, will reveal that the wheel, including its flanges, is actually about 1.4" larger (19.4-inches) than designated.
In order to mount a tire on a wheel, the tire's beads have to slide over a 7/10"-tall wheel flange on one side of the bead seat. Since the tire's steel bead wires don't stretch, this requires the wheel to also feature about a 7/10"-deep tire well/drop center around the wheel adjacent to the other side of the bead seat. This helps avoid damaging the tire's bead by allowing it to maintain its manufactured diameter when being mounted.

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Step 3 of 7
<p><strong>Drop Center Angle</strong></p><p>Another way to tell which side to take a tyre off, is by looking at the steepness of the sides of the drop center. The tyre needs to be removed from the steeper side (green lines).</p>

Drop Center Angle

Another way to tell which side to take a tyre off, is by looking at the steepness of the sides of the drop center. The tyre needs to be removed from the steeper side (green lines).

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<p><strong>How to Tell With a Tyre On</strong></p><p>When the rim has a tyre on, as most cases, it make it a bit more tricky to identify, as you are unable to see inside.</p><p>Instead, you have to look at which side is shortest to the well and which side is steeper</p><p>In this photo the side closest to the camera will be on top when changing this commercial tyre.&nbsp;</p>

How to Tell With a Tyre On

When the rim has a tyre on, as most cases, it make it a bit more tricky to identify, as you are unable to see inside.

Instead, you have to look at which side is shortest to the well and which side is steeper

In this photo the side closest to the camera will be on top when changing this commercial tyre. 

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<p><strong>How It Looks on a Tyre Machine</strong></p><p>See the photo for how the rim should be placed on the tyre machine.&nbsp;</p><p>As you can see the shorter side is on top as this is the side the beads will be taken off on.&nbsp;</p>

How It Looks on a Tyre Machine

See the photo for how the rim should be placed on the tyre machine. 

As you can see the shorter side is on top as this is the side the beads will be taken off on. 

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<p><strong>How It Looks for a Commercial Rim</strong></p><p>As you can see the shorter or steeper side is at the top.</p><p>For most commercial rims the standard orientation is with the disk-face down, to break and remove the first bead (see photo). Hence on an "upside down" rim the the disk-face is at the top, for removing the first bead.&nbsp;</p><p></p>

How It Looks for a Commercial Rim

As you can see the shorter or steeper side is at the top.

For most commercial rims the standard orientation is with the disk-face down, to break and remove the first bead (see photo). Hence on an "upside down" rim the the disk-face is at the top, for removing the first bead. 

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Thank you for viewing these instructions on how to identify the orientation of rims. You should now have a greater understanding on this topic.