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RC090's on a series one .

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olympia57
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RC090's on a series one .

Post by olympia57 » Fri Aug 03, 2018 9:11 am

Anyone running these on a series one ?
If so do they catch on the front arch at any point ?
I had a set of 17 inch et20 wheels with 225/45 tyres on the car when i bought it and they caught on the rear of the front arch on less than full lock.
I've got an offer of a set of RC090's but don't want a contact problem .
TIA
Don
1981 635 series 1

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sharkfan
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Re: RC090's on a series one .

Post by sharkfan » Fri Aug 03, 2018 1:50 pm

What width were the rims?
2001 Alpina B10 V8 Touring (1 of 12 rhd)
1997 Alpina B12 5.7 L (1 of 2 rhd)
1995 Alpina B10 4.6 Touring (1 of 1 rhd)
1985 BMW M635CSi (1 of 524 rhd)
1982 BMW 635CSiA (1 of 100's left from the 1000's made and still valiantly fighting against a rusty grave)

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olympia57
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Re: RC090's on a series one .

Post by olympia57 » Fri Aug 03, 2018 10:16 pm

The rims that rubbed the arch were Lenso RX copies 8x17 et20 with 225/45 tyres.
They just caught the very bottom of the rear of the front arches on near full lock.
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IMGP0004 (Large).JPG (493.35 KiB) Viewed 602 times
The , now secured , RC090's are ex e39 8x17 et20 and I hope to be able to fit a set of Kumho 235/45/17 tyres I have to them once restored.
Hopefully they won't rub on arch or the strut...... [-o< .
1981 635 series 1

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Brucey
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Re: RC090's on a series one .

Post by Brucey » Fri Aug 03, 2018 10:46 pm

235/45-17 tyre is bigger all round (width and diameter) so if 225/45-17 rubbed on wheels with the same offset and width, the new ones will do too.

FWIW I had 235mm tyres on ET15 rims on a series one car and they rubbed in the back of the wheel arches too.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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sharkfan
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Re: RC090's on a series one .

Post by sharkfan » Sat Aug 04, 2018 9:07 pm

It sounds like you need the E31 RC 090's with the 8x17 ET10 front wheel offset.
2001 Alpina B10 V8 Touring (1 of 12 rhd)
1997 Alpina B12 5.7 L (1 of 2 rhd)
1995 Alpina B10 4.6 Touring (1 of 1 rhd)
1985 BMW M635CSi (1 of 524 rhd)
1982 BMW 635CSiA (1 of 100's left from the 1000's made and still valiantly fighting against a rusty grave)

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Brucey
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Re: RC090's on a series one .

Post by Brucey » Sat Aug 04, 2018 11:14 pm

doesn't a reduced offset result in more danger of rubbing, not less, on series 1 cars? They lack the double-knuckle arrangement of series two cars and this means the upright rotates around a fixed pivot (rather than a virtual pivot that moves around as per the series 2 cars).

My impression was that the outside corner of each tyre could scrape against the back of the wheel well (on about half lock) if the wheel/tyre was wide enough and the offset was small enough on the wheel. This may not be the only way wide wheels can rub though, I suppose; IIRC there were signs that the tyre had also rubbed on one of the control arms (nearer full lock I think), and this would be made less likely with a lower offset wheel.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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olympia57
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Re: RC090's on a series one .

Post by olympia57 » Sun Aug 05, 2018 2:39 pm

As the series one has a slightly wider rear track I wouldn't / couldn't go lower than the et 16 that are on just now.
Dropping the et to 10 would only exacerbate the rubbing issue on the front.

After trying several tyre comparison sites and allowing for any slight variations from manufacturer to manufacturer it seems the 225/50/16 ( that are currently fitted ) is virtually a facsimile of the 225/45/17 in profile so it may be that the problem would be slight or even non existent as they do not rub or catch at present.
ET20 may rub on the strut but if so a suitable spacer will solve that .

Surprised that no series one owners with RC090's have dropped by ....

Will let you know how it works out.
Don
1981 635 series 1

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sharkfan
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Re: RC090's on a series one .

Post by sharkfan » Sun Aug 05, 2018 8:36 pm

Far from me to argue against Brucey but ET10 wheels for any same width will sit 10mm further OUT than ET20; if the wheel arch at the critical point narrows from the outside to the inside then this should give more clearance, if however the wheel arch widens from the outside to the inside then it might give less clearance.

The E31 wheels share the same hub diameter as E12, E23/4/8 and E32/34/38 so don't need the hubcentric centres of the E39 car wheels.

Fitting E31 wheels with 10mm different offset to an E12, E23/4/8 and E32/34/38 will increase the track width by 20mm and should give greater clearance from inner wheel arch rubbing.
2001 Alpina B10 V8 Touring (1 of 12 rhd)
1997 Alpina B12 5.7 L (1 of 2 rhd)
1995 Alpina B10 4.6 Touring (1 of 1 rhd)
1985 BMW M635CSi (1 of 524 rhd)
1982 BMW 635CSiA (1 of 100's left from the 1000's made and still valiantly fighting against a rusty grave)

User avatar
olympia57
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Posts: 1106
Joined: Thu Sep 13, 2012 1:47 pm
Location: Ireland

Re: RC090's on a series one .

Post by olympia57 » Sun Aug 05, 2018 9:23 pm

I've been offered and provisionally bought a set of ET20 wheels at a good price , these are the ones that I'm asking the question about .
1981 635 series 1

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Brucey
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Re: RC090's on a series one .

Post by Brucey » Mon Aug 06, 2018 12:25 am

sharkfan wrote:
Sun Aug 05, 2018 8:36 pm
Far from me to argue against Brucey but ET10 wheels for any same width will sit 10mm further OUT than ET20...
that is what causes the rubbing, IIRC (it certainly did with the wheels I had in an E12 based chassis); the outer edge of the tyre rubs in the back of the wheelarch, and the further away it is from the kingpin axis (or whatever you want to call it) the more likely that type of rubbing will be. It may not be the only form of rubbing though, as also noted upthread.

BTW a 225/60 tyre may not be the same width across the tread cap as a 225/50 tyre and anyway it may vary from one manufacturer to another. Those two tyres will also differ in width at the central part of the sidewall bulge; if the tyre is rubbing on a control arm this could make a difference too.

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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olympia57
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Re: RC090's on a series one .

Post by olympia57 » Mon Aug 06, 2018 2:38 pm

Got a reply from Rob Siegal ( hack mechanic ) who has a set of RC090's et20 225/45 fitted to a series one and he tells me that there was no rubbing issues with them at all.
Don
1981 635 series 1

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