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Old 10-20-2008
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15x8 Backspacing/Offset

I am looking for pics or info on 15x8 RWD Wheel with -27 offset.
I would like to see what its look like or if this is in the ball park of what offset I need so I can order my wheels.
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Old 10-24-2008
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I'm not sure what "-27" offset means?

My stock wheel & my set of alcoa's measure 106mm from the hub flange to the outside of the inner lip.

And my MT classic II measure 80mm. (pushes the tire outward 26mm)

Rich
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Old 10-24-2008
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alot of us know more back spacing measurements that would be more helpful
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Old 10-24-2008
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4" BS is ideal correct?

My rims are like 4.25" though... that shouldnt be too bad though right?
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Old 10-24-2008
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usually 3.75-3.25 are the norm for 15x8...
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Old 10-24-2008
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Quote:
Originally Posted by .ender View Post
4" BS is ideal correct?
Well "ideal" is relative to what tire is being used as well as how wide the rims are.

My stock wheel measures 106mm = 4.17" (assuming I measured from the proper points on the rim)

Rich
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Old 10-24-2008
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guys -27mm offset is a backspace of 2.94" on a 8" wheel but if youlook at the diagram backspacing includes the lip, the lip is about .25" so id say the backspacing is 3.25" ish

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Old 10-24-2008
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Well if it includes the lip my measurements are a little short.

BTW, the "-27" can't be in metric. 27mm = 1.063" And these wheels are much deeper than that.

I'll remeasure mine tonight. (have some very accurate 12" digital calipars)

Rich
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Old 10-24-2008
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Quote:
Originally Posted by wydopnthrtl View Post
Well if it includes the lip my measurements are a little short.

BTW, the "-27" can't be in metric. 27mm = 1.063" And these wheels are much deeper than that.

I'll remeasure mine tonight. (have some very accurate 12" digital calipars)

Rich
???????????????????


Offset is from the center of the wheel to the WMS(wheel mount surface)

If the offset if negative it is a deeper dish wheel, positive it is not as deep.

Offset is ALWAYS done in metric, ALWAYS.

a -1.06 or -27mm. a 8" wide wheel half is 4.

4" - 1.06" = 2.94" add the lip and you get around 3.25" of backspacing.

Can you see the diagram I posted Rich?
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Old 10-24-2008
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So your saying "offset" is referenced to the stock rim? So, my new MT classic IIs would have an offset of "27mm" as comparied to the stock rims.

I gotcha now... I thought "offset" just meant the measurement from the axle hub face to the lip on the rim.




Rich
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Old 10-24-2008
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Rich ALL STOCK ford wheels are 4.5" back spacing...
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Old 10-24-2008
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No not just stock rims any rims.

Offset is the measurement from the center of the wheel to the mounting surface.

Backspace is from the back or the rim to the mounting surface.

backspace is normally always in standard units and Offset is always in metric.

So to make it really easy... here is an example

stock wheels are 7" wide with 4.5" of backspacing. the center of the 7" wheel is 3.5" from the front lip and 3.5" from the back lip. as stated above backspacing is from the back lip of the wheel to the hub mating surface is 4.5".

This means that the stock wheel has roughly +1" of offset.
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Old 10-24-2008
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Beard i never said offset...

edit i think your talking to Rich now i think about it..
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Old 10-24-2008
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I get it. It's what I'd call "industry jargon". The measurements makes sense once you know what the "base" is.

From a vehicle dynamics standpoint, the center of the tread touching the road back to the hub is what places increased or decreased loads on the suspension. The more outward the tire.. the higher the loads on things like wheel bearings, ball joints, springs, control arms, & shocks.

Rich
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