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what is the offset...?

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it is zero, the back spacing will change upon width of the wheel usually that is around 3 to 3.5 inches

Originally posted by ZmeFly

it is zero, the back spacing will change upon width of the wheel usually that is around 3 to 3.5 inches

ZmeFly:

Since yur an alignment tech I'm hoping that you can 'splain this to me so I understand it.

I thought that if the "offset" was zero, then the back-spacing would be exactly 1/2 of the wheel width. In other words:

5" wide wheel = 2.5" back space

5.5" wide wheel = 2.75" back space

6" wide wheel = 3.0" back space

7" wide wheel = 3.5" back space

8" wide wheel = 4.0" back space

Reason I ask is I've seen people post wheel size info that doesn't follow this assumption. Can you clear this up for me? I'd appreciate it. Thanks.

S
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Originally posted by BambiKiller240

The way I read that web page seems to confirm my previous statements. With ZERO offset, back-space should be 1/2 of rim width.

YES / No?

Seems that way.

However, 7" wheel may measure 8" from the edge to the edge, 7" being inside of the edge where the tire mounts. That's why the chart for 7" rim shows 4" backspace for 0mm offset.

Now this is where it seems GOOFY to me. The GIF image on that page shows measuring the "backspace from the "outer edge" of the inner side of the wheel to the mounting surface. The measurement from there INCLUDES the (one) "lip" of the wheel. I always thought the Width of the wheel was measured from outer edge to the other outer edge? It seems to me that he measurement from the mounting pad to the "other" outer lip should be equal, or the offset is NOT zero. WTF??

i should have put that in my post as per a 15x7 wheel

sorry

Originally posted by BambiKiller240

Now this is where it seems GOOFY to me. The GIF image on that page shows measuring the "backspace from the "outer edge" of the inner side of the wheel to the mounting surface. The measurement from there INCLUDES the (one) "lip" of the wheel. I always thought the Width of the wheel was measured from outer edge to the other outer edge? It seems to me that he measurement from the mounting pad to the "other" outer lip should be equal, or the offset is NOT zero. WTF??

The wheel width is specified from the inner lip to inner lip, 15x7 wheel would have 7" for tire mounting. However, if you measure the wheel width from out to outer edge, it will be larger by .5" to 1". Since the graphic shows you how to measure the backspace from the outer edge, that's why it may seem to be goofy, but it's really not. And yes, if the wheel is 0mm offset, then measuring from either side should yield the same results.

Also, if you measured the diameter of 15" wheel from outer to outer edge, it will be 16" :classic:

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