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offset 16x7 on a 940

Ursan

Ursan

Bored Member
Joined
Jun 14, 2004
Location
Satan's Kingdom, Ma.
I searched, but didn't locate anything specific.

I'm looking to get some 16x7 steelies and wanted to know the proper offset.

740/940 uses 25mm offset? This okay with a 7" rim?
 
They're both ways to measure the spacing, but the numbers aren't interchangable. Back space is measured from the rear bead of the rim, (usually in inches) and offset from the centerline in millimetres.
 
Offset is the distance between the center point of the wheel width and the mounting face that goes against the hub. It must be used in combination with wheel width to convey any meaningful information. 16x7 with 25mm offset will clear the strut tube in a 940, but 16x12 with 25mm offset would not. Backspacing is WAY different.

Backspacing is a measurement from the mounting face that goes against the hub to the inner edge of the wheel (some may say innermost edge, some may say to the tire bead which will be about 3/8" to 1/2" shy of the innermost edge).

A 7" wheel will measure about 8" overall width. The mid point is 4". The offset is positive. So add the 25mm offset to the 4" and you get ~5" backspacing.

16x12 with 25mm offset.....6.5" is the mid point, so backspacing is ~7.5". Big difference between two wheels with the same offset.

I thought Gemini were 20mm offset, but I don't have any to check.
 
Ursan said:
Thanks.

25et is the same as backspace?
Click to expand...

Sort of but not really. They are related.
ET (or offset) is the distance between the centreline of a wheel and the mounting face.
Backspace is the distance between the inner edge of the wheel and the mounting face.

Have a look here:
https://www.rsracing.com/TechWheel.aspx

For information, in the UK some 940s (the 940 Sport Edition) came with 16x7 et20 Galaxy wheels as standard.
 
Polaris wheels are also 7" and they are ET20.
I have 8" on 16" and they are ET11 and with 40mm lowered springs and HD billies and with 215/55/16 I am slightly hitting the tire both front and rear on 940 MY95.
I am going to adjust 17"x 7" steelies on ET17
 
I have a set of Geminis on a 91 945. My Nivomats died this weekend just as I was moving a very full station wagon. I was almost on the bump stops, and the wheel was way up in the wheel well.
Drove 400 miles that way, with only slight rubbing, so you should be ok.
 
Ursan said:
So, 16x7" 5x108 (5x4.25") with 5" backspace is what I want?
Click to expand...

You could go 4.5 inch backspacing. As others have said, the factory 16x7 are +20, which are lower offset than wheels with 5" backspacing, I think. So 4.5" should still fit, fill the fenders better, and shouldn't rub, probably. Depends on your tires.


What wheels are you even looking at btw?
 
205/55-r16 front and 215/55-r16 rear on 16x7" et20 galaxys here. The back rims couls have slighly lower et (10-15 maybe, nowhere near rubbing now), the front looks good IMO.
 
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