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15 x 7 wheels to replace TRXs

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Dimi555
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15 x 7 wheels to replace TRXs

Post by Dimi555 » Mon Jul 02, 2018 3:35 pm

Dear all,

I have a white 1988 M6 (imported to the States from Europe in 2004).

I plan to buy five 15 x 7 refurbed wheels to finally replace the crummy old TRXs and get the car back on the road.

What size tires should I put on them?

Any advice would help.

Thanks.

Dimi555
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Re: 15 x 7 wheels to replace TRXs

Post by Dimi555 » Mon Jul 02, 2018 5:18 pm

I should add-- I was thinking hard about going with 17" BBS from my old E39, but I want to keep the classic look (for now). Maybe someday I'll go with the 17's, but I want the car to look as period correct as possible.

Here are the tires I will go with:
59168.jpg
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brickwhite
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Re: 15 x 7 wheels to replace TRXs

Post by brickwhite » Tue Jul 03, 2018 12:21 pm

a 16" wheel would be closer to stock size,

alot of people I know use the e38 16" wheel with good results.

Image

Here are some in NJ painted black...

https://cnj.craigslist.org/wto/d/bbs-bm ... 41490.html

https://newyork.craigslist.org/brk/wto/ ... 62631.html

for $250

my .02
- 12 535i
- 92 325ic
- 88 535is
- 85 M635csi

- 63 Triumph Tr-4

Dimi555
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Re: 15 x 7 wheels to replace TRXs

Post by Dimi555 » Tue Jul 03, 2018 3:38 pm

I know most people go with 16's, but I thought the oem TRXs were 15.4" in diameter.

Does it really make a difference?

I just don't know what tires to go with for the 15's. Any advice here would help. I obviously don't want to go too small.

Dimi555
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Re: 15 x 7 wheels to replace TRXs

Post by Dimi555 » Wed Jul 04, 2018 2:01 am

Ah shhhhhh....

I see my mistake now. The TRXs on the Ms were 16.34 inch rims, not 15.4". I guess the 15.4" rims were on the 635csi (non-M version). I'm going to go with 16"s.

That would indeed be closer to the original look.

Thanks for the feedback.

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Brucey
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Re: 15 x 7 wheels to replace TRXs

Post by Brucey » Fri Jul 06, 2018 7:49 am

I've posted this many times before but the 15" (or 16") rims are 15" (or 16") at the bead seat diameter and the standard TRXs are ~15.4" (or 16.4") at the bead seat diameter.

However the rim lips are different heights, with the TRXs having smaller lips. This means that the 15" wheels (measured lip to lip) are almost exactly the same OD as the smaller TRXs and similarly 16" rims are almost exactly the same size as the larger TRX rims.

So in terms of exposed tyre sidewall height, stock looks, and basic handling, you should use 15" rims in place of the smaller TRXs and 16" rims in place of the larger TRXs.

However one thing that does vary is the clearance between the rim well and the brakes; in some cases a TRX wheel will fit over a brake where an inch-sized wheel won't fit. This is most likely to happen with M6/M635 CSi models; the brakes can foul inside some 16" rims that have deep wells and/or thick barrels.

IMHO an important reason for wanting to use 17" rims on an E24 is just that there is more choice of cheaper rubber to fit on them; these days there is less choice of good 15" and 16" tyres and you may have to pay a premium for these tyres. By comparison 17" fitments are more numerous and prices are subject to more competition. All things being equal, expect ride comfort and noise to deteriorate with larger wheels.

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

Dimi555
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Re: 15 x 7 wheels to replace TRXs

Post by Dimi555 » Fri Jul 06, 2018 2:00 pm

Hey Brucey,

Great post; thanks for the info. I hear you on the 17" tires being more abundant and affordable, but I found a set of 16" rims and tires from an E39, that I will (try to) use. I simply don't like the look of the 17"s on the shark.

I know I will have to get the hubcentric rings and I hope that there won't be any clearance issues with the brakes. I will keep you all posted on how this goes.

Here are the wheels I want to buy:

OEM BMW Aluminum Alloy - BMW Part No. 36111182277
size 16X8" with a 5x120mm bolt pattern, 8JX16 ET:23
CROSS-SPOKE STYLING - Style #5- Basketweave
caps included


Any more advice or thoughts on the matter are highly appreciated.

Regards,
Dimi
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brickwhite
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Re: 15 x 7 wheels to replace TRXs

Post by brickwhite » Fri Jul 06, 2018 3:10 pm

Those are 16"s from a e38 (7 series) shouldn't need hub rings.

You won't find new 235 wide tires.. but a 225/50/R16 will work for that wheel.

https://www.discounttiredirect.com/fitm ... /225-50-16
- 12 535i
- 92 325ic
- 88 535is
- 85 M635csi

- 63 Triumph Tr-4

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Brucey
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Re: 15 x 7 wheels to replace TRXs

Post by Brucey » Fri Jul 06, 2018 5:24 pm

235/60-16 tyres are way too big to fit in E24 wheelarches, so really you buying wheels not tyres there. That size tyre was used on E38, not on E39.

If E38 wheels they should fit OK ((*) although I am not 100% sure about brake clearance on an M6/M635CSi come to think of it)

once fitted with smaller tyres eg 225/50-16 as suggested above.

If they really are E39 wheels (unlikely IMHO) they won't fit without using hubcentric rings.

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

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wattsmonkey
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Re: 15 x 7 wheels to replace TRXs

Post by wattsmonkey » Mon Jul 09, 2018 7:20 am

I'm pretty sure there is a 16" E39 style 5 - 7 1/2" as opposed to 8" and ET20 rather than ET23.

I'm thinking back to my E28 M535i days, when I was annoyed to find that 225/50r16 tyres would rub on the front struts with the E38 ET23 wheels, hence going down to 205/55r16 on the front. I didn't actually find any of the E39 wheels, mind!

17" for me, just because Michelin PS4 available at a reasonable price, although I completely agree that 16s look better and ride better.


The specs for these style 5 wheels are stamped under the centre cap iirc.
"Most of it necessary; all of it enjoyable[!]" LJKS
'86 M635CSi #367 Bring the Noise.
'84 635CSi, dogleg fun

Dimi555
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Re: 15 x 7 wheels to replace TRXs

Post by Dimi555 » Tue Jul 10, 2018 2:53 am

You guys were right. The rims look great, but the tires are indeed too big.

I picked up the wheels and tires on Sunday in Brooklyn. The tires weren't in the best shape either, so I don't mind getting a new set. The rims are in great shape, and at $100 a piece, they better be.

Now I gotta buy some tires.

These wheels are from an E38. A 2001 740il, to be precise.

So Brucey, do I not need the hubcentric rings?

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hornhospital
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Re: 15 x 7 wheels to replace TRXs

Post by hornhospital » Tue Jul 10, 2018 3:12 am

I'm not Brucey, but I can tell you that hubcentric rings are NOT needed with those wheels. They have the correct 72.56mm hub bore that most BMWs (including our E24s) have. The only 5 x 120 bolt pattern BMW wheels that require adaptor rings are those from E39s, which for some reason BMW decided needed to use a 74.1mm hub.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"

Dimi555
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Re: 15 x 7 wheels to replace TRXs

Post by Dimi555 » Tue Jul 10, 2018 2:37 pm

Dear all,

Ok, good to know I don't need the hubcentric rings-- one less thing to worry about.

Now, the question is will 225/50r16 rub the struts, or will I have to go with 205/55r16's.

Man, this is complicated.

PS- I did put one of the 235/60-16's on the front right for shits-n-giggles and it was really pressed against the strut-- didn't even bother lowering the jack before I put the TRX back on. Didn't notice any issues with the brake and the rim making contact-- so far.

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Brucey
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Re: 15 x 7 wheels to replace TRXs

Post by Brucey » Tue Jul 10, 2018 5:39 pm

Dimi555 wrote:
Tue Jul 10, 2018 2:37 pm
…..Now, the question is will 225/50r16 rub the struts, or will I have to go with 205/55r16's.....
IME it will vary with the exact construction of the tyre. Not all tyres of the same width are built in the same way; years ago I downloaded the full Michelin tyre catalogue as a pdf and at the time they had several different tyre models in many common sizes together with exact dimensions for each. There were often substantial differences between what should (or at least could) have been virtually identical tyres.

A get out jail free card is potentially to use a thin wheel spacer at the front. Whether you lose the hubcentric location or not (which would be very bad indeed) is dependent on the length of the paralell part of the hub spigot and similarly the depth (if any) of the counterbore in the wheel. These things vary quite a lot but in most cases you can fit a ~3mm spacer without buggering everything up.

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

Dimi555
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Re: 15 x 7 wheels to replace TRXs

Post by Dimi555 » Wed Jul 11, 2018 1:44 am

Ok. Well. I ordered some 225/50r16 contis. Tire place will mount and balance on Thursday and if they still rub, we'll explore the spacers or thinner tires.

Thanks for all the helpful info.

Dimi555
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Re: 15 x 7 wheels to replace TRXs

Post by Dimi555 » Thu Jul 12, 2018 1:53 am

I had some time this afternoon and the tire shop had the wheels so I had them put on the M6. These are the Continental 225/50r16's on the E38 wheels, and ...

they fit!

But there is not much clearance at all. We had to use flashlights to confirm there was no contact since it was pretty hard to tell, although no rubbing sounds were also a good indicator.

If I want to add the spacers just for a larger buffer, which do you recommend?

The car looks great. Pictures forthcoming!

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Brucey
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Re: 15 x 7 wheels to replace TRXs

Post by Brucey » Thu Jul 12, 2018 3:51 pm

I'd drive the car and see if there is really contact when driving or not, before opting for spacers. If you do use spacers, 'as thin as possible' is the way to go.

Otherwise, it sounds like success!

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

johnn635
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Re: 15 x 7 wheels to replace TRXs

Post by johnn635 » Fri Jul 13, 2018 12:02 pm

FWIW I fitted the E38 16" fitted with 245/45 tyres but found you needed a 5mm spacer because of the 23mm IS of the E38 wheels. In turn, because the wheel has an inner chamfer, a plain spacer leaves the wheel scarcely engaged on the hub, and is relying on the bolts to centre and support the wheel.
You need a spacer which has the hub projection, or you drive it gently!
John

Dimi555
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Re: 15 x 7 wheels to replace TRXs

Post by Dimi555 » Mon Jul 23, 2018 12:19 pm

Hello John, thanks for the info. Everything seems ok sans spacers and the 225/50r16s. So glad to be done with the trxs. Now i gotta rebuild or replace both front calipers (i will likely replace with calipers overhauled by someon else).

The M6 should be drivable just in time for me to winterize her. :-?

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