I got a whole new car for < US$ 5 000
09-26-2005, 12:50 PM
#31
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My Ride: -SOLD- 530i Alpine White. Sport package, comfort seat package, premium sound package, power rear shade, premium package, rear red reflectors, and adaptive headlights with xenon’s
Very sweet lookin
09-26-2005, 01:02 PM
#32
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Originally Posted by das' date='Sep 26 2005, 10:28 PM
[quote name='BMW#5' date='Sep 26 2005, 01:57 PM']Based on the formulae above, l calculated that the rear M172 wheel sticks out approx 24mm if the 172 wheel is 9"wide or 30mm if the 172 is 9.5" wide.
Something is clearly not right. Das, anyone... ideas?
Something is clearly not right. Das, anyone... ideas?
19 x 9.5: 9.5" wide, ET 32mm (1.26" offset) = 4.75" (wheel centerline) + 1.26" offset = 6.01" distance from hub
Is that not correct? The offset is only the positive or negative difference from the centerline of the wheel.
Attachment 10815
[snapback]175293[/snapback]
[/quote]Ok so Style 135
18 x 8: 8" wide, ET 20mm (0.79" offset) = 4" (wheel centerline) + 0.79" offset = 4.79" distance from hub,
and
172 wheel, 19 x 9.5: 9.5" wide, ET 32mm (1.26" offset) = 4.75" (wheel centerline) + 1.26" offset = 6.01" distance from hub
Which gives:
6.01" - 4.79" = 1.22" or 30mm more offset from hub on 172 rear wheels vs 135 rear wheels.
I could beleive a 15mm difference, but 30mm is just not possible. Could we be neglecting a factor of 2 somewhere in the calculation?
I'm getting a woodie with all this tech talk too.
09-26-2005, 05:15 PM
#38
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Originally Posted by BMW#5' date='Sep 26 2005, 03:02 PM
Ok so Style 135
18 x 8: 8" wide, ET 20mm (0.79" offset) = 4" (wheel centerline) + 0.79" offset = 4.79" distance from hub,
and
172 wheel, 19 x 9.5: 9.5" wide, ET 32mm (1.26" offset) = 4.75" (wheel centerline) + 1.26" offset = 6.01" distance from hub
Which gives:
6.01" - 4.79" = 1.22" or 30mm more offset from hub on 172 rear wheels vs 135 rear wheels.
I could beleive a 15mm difference, but 30mm is just not possible. Could we be neglecting a factor of 2 somewhere in the calculation?
18 x 8: 8" wide, ET 20mm (0.79" offset) = 4" (wheel centerline) + 0.79" offset = 4.79" distance from hub,
and
172 wheel, 19 x 9.5: 9.5" wide, ET 32mm (1.26" offset) = 4.75" (wheel centerline) + 1.26" offset = 6.01" distance from hub
Which gives:
6.01" - 4.79" = 1.22" or 30mm more offset from hub on 172 rear wheels vs 135 rear wheels.
I could beleive a 15mm difference, but 30mm is just not possible. Could we be neglecting a factor of 2 somewhere in the calculation?
[snapback]175308[/snapback]
Let's take a look at this diagram again:
I have been adding A + C to get B, the rim's "backspace", and those calculations are indeed correct. But what we are looking for is the distance from the wheel's bolt face to out outer edge of the rim, in other words, not A + C, but A - C (or, 2A -
. So let's try this again:Style 135
18 x 8: 8" wide, ET 20mm (0.79" offset) = 4" (wheel centerline) - 0.79" offset = 3.21" distance from hub
Style 172
19 x 9.5: 9.5" wide, ET 32mm (1.26" offset) = 4.75" (wheel centerline) - 1.26" offset = 3.49" distance from hub
Which gives:
3.49" - 3.21" = 0.28", or 7mm more offset from hub on 172 rear wheels vs 135 rear wheels.
Now let's do the fronts:
Style 135
18 x 8: 8" wide, ET 20mm (0.79" offset) = 4" (wheel centerline) - 0.79" offset = 3.21" distance from hub
Style 172
19 x 8.5": 8.5" wide, ET 18mm (0.71" offset) = 4.25" (wheel centerline) - 0.71" offset = 3.54" distance from hub
Which gives:
3.54" - 3.21" = 0.33", or 8.4mm more offset from hub on 172 front wheels vs 135 front wheels.
Does that look better?
------
Soooo...width still comes into play, but I was just figuring the wrong dimension!
For what it's worth, this also means that the Style 172 wheel is inset an additional 4mm than the Style 166 wheel on the rear, and 6mm on the front. And that answers my worries about the Style 166 sticking out too much on the xi; the Style 172 seems like it will work just fine:
Style 123 (for reference)
4" - 0.787" offset = 3.213"
Style 172
Front: 4.25" - 0.709" offset = 3.541" - 3.213" = 0.328" (+8.33mm)
Rear: 4.75" - 1.260" offset = 3.490" - 3.213" = 0.277" (+7.04mm)
Style 166
Front: 4.25" - 0.472" offset = 3.778" - 3.213" = 0.565" (+14.35mm)
Rear: 4.75" - 1.102" offset = 3.648" - 3.213" = 0.435" (+11.05mm)
Based on that information, I feel comfortable ordering the Style 172 for my own car.
09-26-2005, 11:33 PM
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Man, I love those wheels. They are now on my wishlist, they look absolutely brilliant, better even than the M5 wheels.
However, Mrs Shiny hates you, as she's not getting a new kitchen now
However, Mrs Shiny hates you, as she's not getting a new kitchen now