1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

stock wheel measurements

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Old Mar 7, 2002 | 05:54 AM
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stock wheel measurements

Does anyone know the frontspacing and backspacing measurements for the stock wheels (12A)? I know they are 13x5.5" but I need backspacing and frontspacing measurements to compare with another set of wheels. If anyone has one lying around they can measure that'd be great.

Thanks,
Mike
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Old Mar 7, 2002 | 06:49 AM
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25mm offset. That makes for, ah, uh, carry the seven... 3.75" backspacing. That's putting the tire extremely close to the strut, so it would be a bad idea to have more backspacing than that on a 12A car. (13B cars have 40mm offset for the same rim width - their hub face is 15mm further outboard)
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Old Mar 7, 2002 | 09:19 AM
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what's the difference between offset and backspace?
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Old Mar 7, 2002 | 09:30 PM
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Offset is the difference between the centerline of the wheel and where the hub surface is. There's some debate as to what is "positive" offset and what is "negative" offset.

Backspace is the distance from the hub surface to the inside rim lip. I feel backspace is more important to know because the inside lip is more likely to cause clearance problems. You can always move the fender lip, but it's a bit harder to move the steering arm or the strut housing.

Come to think of it, I was wrong on the backspacing. I didn't figure in the rim shell's width. Let's say 4" backspacing with stock rims.
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Old Mar 8, 2002 | 12:08 AM
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Hmm, that changes things. My main concern is finding out what the frontspacing is on stock wheels. I want to buy a set of wheels, but not if they are set "in" more than stock wheels. I highly doubt this happening, but just want to make sure.

Anyone have the exact measurements on the stock 12A wheels?
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Old Mar 8, 2002 | 12:17 AM
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or actually, does anyone have an unmounted wheel they can measure the exact lip to lip measurement on? This will let me figure things out easier.
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Old Mar 8, 2002 | 12:33 AM
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I don't see how one could even measure "frontspacing".

The way you measure backspacing is to put a straightedge across the inside rim lips and measure from the hub surface to the ruler. If that's more than 4" you can't use the wheels, they will rub on the strut housing.

Don't worry about the front face... if the back side fits, then the front will stick further out. You can't get any further in than a stock wheel without making the rim narrower, as they are as far in as possible for a 5.5" rim.
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