How to calc offset and backspace?

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11-07-2005, 11:02 PM

Cheers!

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How to calculate offset from backspace.

[(backspace) - (rim width divided by 2)] x 25.4 = offset?

please see attached file... Found some Cobra R 17x8 wheels. I know stock mustang GT wheels are +30 offset. But according to this summit racing advertisment, the backspace is 5.72. Which means it's 43 mm?

clarify?

11-08-2005, 07:45 AM

inanimate_object

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they're definitely 43mm offset if that's what you're asking.

Mark

11-08-2005, 10:10 AM

Cheers!

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Quote:

Originally Posted by inanimate_object' post='776543' date='Nov 8 2005, 08:45 AM

they're definitely 43mm offset if that's what you're asking.

Mark

I like those wheels too. Not too expensive. But they frigging weigh 25 lbs!!!! That is baloney slicer territory

11-08-2005, 02:59 PM

inanimate_object

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I reckon superleggeras are still the best weight to cost wheels around.

Mark

11-11-2005, 03:12 AM

kahren

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you did not include rim lip in your formula, that is not part of the wheel width. 8 inch wheel is actualy wider then 8 inches that is why it doesnt work. here is how to do it.

http://www.rsracing.com/tech-wheel.html#backspace

11-11-2005, 04:24 AM

inanimate_object

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If you take into account 1/2" lips on each side (which seems about right to me) you come up with a 30mm offset. You learn something new every day.

Mark