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old: e82 MSport N47 120d. current e82 MSport N52 125i.
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347 Posts
Discussion Starter · #1 ·
One for the suspension experts :)
I think my car's always done this since I've got it. But I'm starting to notice it more.
I'm going quick-ish around a tight roundabout or a 90 degree bend in town and as the steering starts to come back to center the back end of the car does a little skip and I see a flash of ABS. Nothing where you would expect the backend to go at all, and it feels fine on the open road but this little skip feels wrong.
Everything on the rear is as far as I can tell standard apart from the tyre size and offset (See below), the previous owner swapped the wheels for a set off a 440i. The overall outer diameter of the tyres is about 33mm bigger than the stock. and some other differences offset etc:
I'm suspecting it's either somthing to do with that, or there's a failed bushing or shock or somthing. Or could it just need an alignment perhaps?
Any thoughts?



The difference in the stock and current tyre settup:
Front StockFront CurrentDifference from Stock
Width mm
215.00​
225.00​
10.00​
Profile %
40.00​
40.00​
0.00​
Rim Diameter In
18.00​
19.00​
1.00​
Rim Width In
7.50​
8.00​
0.50​
Rim Offset (mm)
49.00​
36.00​
-13.00​
Spacer (mm)
0.00​
0.00​
0.00​
Total Offset (mm)
49.00​
36.00​
-13.00​
Profile (mm)
86.00​
90.00​
4.00​
Diameter (mm)
629.20​
662.60​
33.40​
Radius (mm)
314.60​
331.30​
16.70​
Circumference (mm)
1976.69​
2081.62​
104.93​
Rim Poke (mm)
46.25​
65.60​
19.35​
Inset (mm)
144.25​
137.60​
-6.65​
Track (mm)
1470.00​
1496.00​
26.00​

Rear StockRear CurrentDifference from Stock
Width mm
245.00​
255.00​
10.00​
Profile %
35.00​
35.00​
0.00​
Rim Diameter In
18.00​
19.00​
1.00​
Rim Width In
8.50​
8.50​
0.00​
Rim Offset (mm)
52.00​
47.00​
-5.00​
Spacer (mm)
0.00​
0.00​
0.00​
Total Offset (mm)
52.00​
47.00​
-5.00​
Profile (mm)
85.75​
89.25​
3.50​
Diameter (mm)
628.70​
661.10​
32.40​
Radius (mm)
314.35​
330.55​
16.20​
Circumference (mm)
1975.12​
2076.91​
101.79​
Rim Poke (mm)
55.95​
60.95​
5.00​
Inset (mm)
159.95​
154.95​
-5.00​
Track (mm)
1497.00​
1507.00​
10.00​
 

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What car is it - or more specifically does it have the ediff fitted? I junked mine off as it was doing something similar, when really pressing on it felt it needed to intervene which was unnerving at best and dangerous at worst.

Even if you havent got ediff it might well be the TC getting involved, different tyres from stock can confuse TC systems, I think Im right in saying that even if you think its turned fully off it will still have some effect. Best bet is to try standard wheels and see what happens, Id still get rid of the ediff anyway though ;)
 

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old: e82 MSport N47 120d. current e82 MSport N52 125i.
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347 Posts
Discussion Starter · #3 ·
It's a 125i,, I don't know if they came with the e-diff. But yes i think it could feel like the inside braking.
I'd have swapped the tyres a long time ago but it came with brand-new p-Zero's on it :)
 

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old: e82 MSport N47 120d. current e82 MSport N52 125i.
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347 Posts
Discussion Starter · #5 ·
they are!
Better than others I've tried. they don't seem to follow lines in the road like the Mitchelin's I had on the old 1'er and the 4 series.
I know the sidewalk flex feel you get on run-flats but this is more of a traction loss skip.
 

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I had some elderly Goodyear Eagle runflats on my car when I got it and that rabbit hopped around bends something horrible especially on rough or broken surfaces. Switching to normal tyres made a vast improvement and I dont really notice it any more.
 

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The ‘bunnyhopping’ supposedly happens because there isn’t enough travel in the rear suspension. Runflats will make this more obvious because of the rock hard sidewalls.

Fitting Koni/BMWP bump stops will buy you 15/10mm of travel back, letting the damper sort the skipping out. Cheapest/easiest option here too - at the rear they’re a DIY job in not very long. Goflats will help too, and subframe inserts will reduce the lateral movement/squirmy feeing. I did all 3 over the course of a year or so, and now the only time it has an issue is a single roundabout near me with a drain cover that’s sunk 2” and polished to a perfect shine so even slicks wouldn’t stick to it!
 

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Rear subframe inserts might also help as the way I understand it they firm up the connection between the subframe and car to reduce movement.

I am sure someone will correct me if I am wrong!
 
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