Opinions on these wheels, please?

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Boggie
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Opinions on these wheels, please?

Post by Boggie »

Hi all,

I have a good set of original wheels that only need a basic refurb but they need new tyres all round. The cost of TRX rubber is eye-watering and I reckon for the refurb and a new set of tyre I am looking at a bill of £2,200!

So, I have been looking around for alternatives. Something that is not too far removed from the original wheel style but imperial, so I can have a choice of tyre and an upgrade at the same time and am considering this:

Rondell 0058 wheels
74.1 centre bore
front 8.5j x18 et13
225/40/18
rear 10j x 18 et19
255/35/18

Can anyone tell me if they will fit ok please? They will look like this:

Image
Image
Image
Image

Thanks,
Ian
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Re: Opinions on these wheels, please?

Post by Soperman »

Without personal experience, I'm not able to tell you if they can be mounted or not, but there are clearly no shortage of images suggesting they can at least me made to fit.

Imperial alternatives to metric rims have been discussed countless time on this site, with lots of suggestions, advice and images to help you choose. But what you might struggle to find are people who have experienced, and been happy with, the adverse effect 18" wheels have on both ride and dynamics of E24s.

Whilst 18"s look very impressive and contemporary, it is worth bearing in mind that these cars were originally designed to take rims of circa 14"-15".
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Re: Opinions on these wheels, please?

Post by Boggie »

Thanks and agreed. It was one of my concerns, larger rims = lower profile tyres to retain rolling radius, gearing and speedo accuracy. This introduces the risk of tram-lining and whilst this can potentially be dialled out by adjusting toe-in and castor angles it is a challenge to get right without affecting turn-in and other handling issues.

Aside from tram-lining, what other effects should I consider before fitting larger rims on the M635 E24 please?
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Re: Opinions on these wheels, please?

Post by Boggie »

Some interesting information HERE
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Re: Opinions on these wheels, please?

Post by GazM3 »

The only “real” effects of the larger rims at 2. 1 the extra weight of the wheel /tyre combo (which puts extra pressure on the bushes especially) and 2 the thinner sidewalls u have to run which makes the car ride more harsh.

The upside is the choice of quality rubber that is available.

You have to be also careful with the staffer as u can make it understeer more. If going this path it would be best to setup the front end with more aggressive camber and toe settings which will need modified strut tops or modified offset roll centre adjusters. What helped make my stagger neutral was a thicker rear roll bar and I installed strut top braces both front and rear.

There is not much room on the front with std suspension to install anything wider than a 235 tyre, 225 probably better with the taller 18”. I run on the front 17x9 et12 with a 225/45 tyre and there is only about a finger thickness to the top of the suspension strut assembly. With a 225 on a 9” rim it’s a bit of a stretch look tho.

If considering coil overs the dia of the spring is less then you could potentially install wider tyres.

Good luck.
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Re: Opinions on these wheels, please?

Post by Da_Hose »

I run 225/35-18 in front and 275/35-18 in rear. Wheels are 18X8 front, 18X9.5 rear, with 20 offset on both. Driver rear rubs under heavy compression, but I also run Eibach's. With the low sidewall, I think stock height has way too much wheel well space, and it looks off.

I do not think you can run wider, or taller front though. Not enough space in there.

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Re: Opinions on these wheels, please?

Post by Boggie »

Thanks Jose,

Useful info. However, my M635 TRX tyres are 240 wide so in theory, with the right offset 245/40 fronts on an 8.5 rim should fit?
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Re: Opinions on these wheels, please?

Post by LarryM »

I'm running 245/40-17 tires on BBS RS198 wheels (17 x 8.5 x 13ET) all around, without issues.

That said, I have come to think that 40-series tires may be just a bit too low a profile for these cars, mainly because of the extra stress they place on suspension components. I think next time I buy tires I'll switch to 235/45 -17s. I also believe 17" wheels are the maximum size that should be used on the E24, for reasons of both performance and appearance.
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Re: Opinions on these wheels, please?

Post by Boggie »

LarryM wrote: Sat Mar 03, 2018 8:35 am I'm running 245/40-17 tires on BBS RS198 wheels (17 x 8.5 x 13ET) all around, without issues.

That said, I have come to think that 40-series tires may be just a bit too low a profile for these cars, mainly because of the extra stress they place on suspension components. I think next time I buy tires I'll switch to 235/45 -17s. I also believe 17" wheels are the maximum size that should be used on the E24, for reasons of both performance and appearance.
Thanks Larry,

That's good information. So, if I were to fit

8x17 ET10 with 235/45
9x17 ET19 with 255/40

Both have a similar size sidewall of around 102-105mm and a similar rolling radious to the original TRX setup.

From what you say these should be fine :)
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Re: Opinions on these wheels, please?

Post by wattsmonkey »

If you're talking about BBS RC009 and 010 then they fit just fine...265/40r17 fits fine on the rear, in fact.
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Re: Opinions on these wheels, please?

Post by Boggie »

Exactly! Here they are. Very close to the original look of the M635 BBS metric wheels (albeit a little more dished) but with 'normal' tyre fitment.

They are BBS split rims, RC009 8x17 ET20 (72.5mm CB) fronts and RC010 9x17 ET19 (72.5mm CB) rears. They come with premium rubber (235/45x17 and 265/40x17), between 6 and 7 mm tread all round with no repairs to tyres or alloys. They do need a very small amount of work in that the rears have a little milkiness under the lacquer in a couple of small areas but that will be easy to rectify.

I still have the original M635 metric wheels and 4 good Michelin TRX tyres that I will clean, condition and wrap up before storing them in a dark, dry place. This way I can use the car with the new wheels (and a good choice of reasonably priced replacement tyres) until I decide to sell the car. At that point I refit the Metrics / TRX and sell the split rims separately.

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Re: Opinions on these wheels, please?

Post by GazM3 »

Nice score.

U know u can re-barrel the bbs rs metrics as they have a 16” base. That’s what I’m going to do with mine at some stage
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Re: Opinions on these wheels, please?

Post by Boggie »

Is that with the original M635 BBS split rims? After some issues with the wheels, BMW in the EU these replaced them with 1-piece wheels that look like this:
Image
These are what I have 6 of, included with the car. I also have 10 TRX tyres included, 5 good tyres and 4 with cracked sidewalls and one TRX remould [-X

I plan to fit the 5 good TRX tyres to the best 5 wheels and store them for fitting to the car when I eventually sell it. For now the new staggered BBS split rims will look great (especially the 265 wide rears on 9J dishes....)
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Re: Opinions on these wheels, please?

Post by GazM3 »

Yes only on the split rims they are re-barellable (is that a word)?
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Re: Opinions on these wheels, please?

Post by Boggie »

It is now, and far better than Re-Rimming.......
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Re: Opinions on these wheels, please?

Post by Brucey »

re tyres and wheels; I have run a lot of different setups and for comfort and cost (apart from the cost of tyres) on a standard 635CSi I suggest a set of 225/60-15s and 7" BBS wheels as fitted to lots of E34s.

For M635CSi you can go to 16" wheels (which have exactly the same working sidewall height as the original metrics BTW) and the car will handle nicely on a square set.

There is appeal in 17" rims simply because there is a good choice of rubber that is the right diameter and is a reasonable cost. I currently have 17" wheels fitted with a square set of tyres on my 635CSi and it is OK, but noticeably noisier, tramlinier and less comfortable than on 15s or 16s. Doubtless some tyres would be better than others in this respect.

I have run the car on 18" M-parallel wheels from an E38 with E24-sized tyres

fronts 235/40-18 (645mm dia)
rears 255/35-18 (635mm dia)

on 18x8J (ET13mm) front rims
and 18x9.5 (ET25mm) rears

And with sticky rubber on it went round corners admirably and looked nice but in every other way it was, frankly, a bit crap.

The one thing that will dissuade me from ever running a staggered set again is the tyre wear; every set of tyres I have run on my E24 has to some extent worn the fronts on (both) the shoulders and the rears more in the middle of the tread. The chassis is designed to have the tyres periodically rotated front to rear, to even out the tyre wear. With a staggered set you can't do that, and the result is that you might get as little as 1/3 life out of a set of tyres vs a square set.

BTW up to ~225mm front tyres (or perhaps some narrow 235s with the correct offset to the rims) you can get the scrub radius to be zero or very small indeed and the result is (hurrah!) usually no tramlining. As tyre and rim width increase (and/ or the ET value decreases) this becomes impossible and it basically screws the steering up (*). You can compensate for this to some extent by running more negative camber when wider front tyres are fitted (which pushes the working contact patch away from the centre of the tyre) but this again results in very uneven tyre wear, unless you are spending most of your time on a racetrack.

(*) FWIW most E24s I have driven have had less than perfect steering. Contemporary road tests of RHD cars noted that it wasn't as good as the competition (eg Jags with rack and pinion) but there are so many ways it can be bolloxed (esp on a RHD car) that they usually are well-below par. As well as all the usual things that can ruin it like worn parts, badly adjusted steering boxes, slop in the steering column spline, wrong offset wheels, badly lowered suspension with no camber compensation, there is one thing that wasn't well known until fairly recently (in fact I think I discovered it).

It seems that all RHD cars were fitted with the wrong centre link to the steering; although there are two part numbers (one for LHD and one for RHD) you got the same actual part (for a LHD car) regardless of which you ordered. The same part was also fitted from new in most E24/2 chassis (and for all I know all E28 with M30 engine). The result was that the ball joint with low preload that should see the small loads from the idler arm instead saw the loads from the steering box and would (soon after fitting) start slopping about. Needless to say this makes the steering feel like crap vs what it should feel like.

After a lot of effort my E24 now steers nicely, but it took a long time and lot of work (in multiple areas) to get it just right.

cheers
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Re: Opinions on these wheels, please?

Post by GazM3 »

Nice post Brucy.

I found also on the e24 chassis that the front and rear tower bar brace has a massive improvement to chassis and steering feel. Especially when the bushes are all refreshed and the steering arm bracket is sound.

I have a lot of nice cars in the stable and the e24 is one of the best steering and handling cars I have for feel.

One thing also to mention is the wheel weight has a massive impact when upsizing.

Tyre choice is much better on 17” and better again on 18” but most top end tyres seem to be developed for 19” at the moment.
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Re: Opinions on these wheels, please?

Post by Boggie »

Wow, great info both!

My M635 came with 415 diameter (16 1/3"), 195 (7 2/3") wide, ET19 wheels with 240/45 TRX. My theory is that opting for a very slight increase in rim diameter and width to 17" and 8" respectively and 235/45 tyres should be as close to original fronts as possible so should not affect steering.

I am not too worried about the staggering / tyre swapping issues and I think the 265 wide rears will look great too. However, Brucey's comments on offset have caught my eye: "As tyre and rim width increase (and/ or the ET value decreases) this becomes impossible and it basically screws the steering up"

Changing from ET19 to ET10 offset over compensates for the 8mm (4mm inside and 4mm outside) wider rims, which are increasing from 7.67" to 8", so the inner rim is 5mm further away from the strut. The 5mm narrower tyre (in theory as tyres vary) adds another 2.5mm to this figure so the inner tyre will (again, in theory) be 7.5mm further away from the strut. I thought this was a good thing (considering the stories of tyres scrubbing the strut). The outside of the tyre will be 10.5mm further out: 9mm(offset) + 4mm(rim) - 2.5mm(tyre).

Bottom line is that the total track width at the front has increased by 21mm and offset value decreased by 9. Will this affect my steering noticeably? Or will the 5mm narrower tyre compensate for the ET reduction? OR am I overthinking this and these small numbers will make sod all difference and Brucey is talking about much bigger changes?

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Re: Opinions on these wheels, please?

Post by Brucey »

in the grand scheme of things a small offset and a small scrub radius will be tolerable, but there is no doubt that the steering is better with these things optimised instead; the car will be much nicer to drive. It isn't a coincidence that the OEM wheel fitments have the widths and offsets that they do. Since you have the correct wheels as well, try both; old TRXs are pretty poor tyres but I'd expect you to notice a difference in the steering feel and tendency to tramline.

BTW the 415 metric wheels are often said to be 16 1/3" but this is only the bead seat diameter and the TRX rims have small wells and small lips. As I said before the working (i.e. flexing) sidewall height of a 415mm TRX is identical to a standard 16" rim, which has bigger(taller) rim lips and a smaller bead seat diameter.

The same is true of 15" rims and 390mm TRXs. You can verify either by sitting bare wheel rims side by side; they are (including the lips obviously) the exact same height.

Thus the notion that the TRX sizes are 'between inch sizes' is not correct, not in terms of working sidewall height anyway; they are basically identical to the inch sizes. Going from 415 to a 17" rim and keeping the same overall rolling diameter reduces the sidewall height by 1/2", which is quite a lot, and is quite obvious when you drive the car.

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Re: Opinions on these wheels, please?

Post by Boggie »

Thanks Brucey. Once I have finished restoring the engine bay and rebuilt the engine (and fitted the good TRX tyres to the original rims, MOT etc) I will do a week on both and report back. Buckinghamshire roads are amongst the worse in the country so plenty of scope to compare handling..
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Re: Opinions on these wheels, please?

Post by tschultz »

You will find that 16x7 or so wheels with 205/55/16 tire make the front end of the car feel lighter and easier to switch directions over the equivalent 8" wheel with 225 or 235 width tires. I suspect that having the right tread width on the rim has a lot to do with this. As a wider tire on the same sized width wheel will result in more vague steering. Whereas, a narrow tire on a wider wheel with a slight bit of stretch with add rigidity to the sidewall and improve steering response.

For me, I stick with square tire setups (staggered makes the car drive worse and you get wear issues since you can't rotate). Lately, I also have had less emphasis on tire width and more so on tire compound. If you want a better feeling setup, stick with the narrow tire with the better compound. This means 205 width on 7" wheel, 225 width on 8" and 235 width on 9" rim.
A lot of people go for the biggest possible and it actually does make a difference, usually to their detriment. Visually the tire width doesn't matter much, I think it is the wheels (offset and style) that give an aggressive or standard look.

From my reading about sidewall height, I read that you don't want to go to a lower profile than 45 sidewall height or you actually begin to lose steering response and grip levels. That sidewall will absorb some energy for acceleration before totally losing grip and sliding.

I haven't run many 15" wheels, but the light weight is a big plus over 17" wheels. They also give you a bit more comfortable ride... I prefer 17" for looks, and 16" for overall compromise with tire selection.
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Re: Opinions on these wheels, please?

Post by Boggie »

Thanks!

One of the main reasons I chose 235/45x17 was the information supplied by Francoid, a little over halfway down THIS THREAD where he says:
francoid wrote: Wed Jul 13, 2016 2:55 pm Disclaimer: I used to be the global head of sports tires at Michelin in France and created the Pilot Sport line. So I have some knowledge but also some bias...

I would never put 18" on an E24, at least not on a stock one. One would have to modify thoroughly all the suspension elements to go to 18". The car is optimally balanced with 225/50R16 or 235/45R17 all around.

There is nothing magical about increasing the diameter of the rim. It's 99% marketing fad. In some ways it can be counter productive as it increases the unsprung mass. The wheel itself does pretty much nothing. It's the tire that actually does the work, as we all know, and as such it's really the measurements of the tire that matter.

The most important measurement is sidewalk height. The sidewalk of the tire is the part that has to flex the most to provide the required performance elements (in particular handling and comfort). We did a lot of research and trials and found the following optima for the pseudo sidewalk height (nominal width * aspect ratio, so for example 235 * 45 = 106):

Light, track oriented sports cars (Ferrari 348, Porsche 911): 90 to 100 mm
GT type sports cars (E24 M6, E34 M5, Porsche 928): 100 to 110 mm
GT not tuned for sport (E24 635, E34 535): 110 to 120 mm
Heavy, comfort oriented (most E31 and E32, Jaguar, typical class S): 120 to 130 mm

These were found to be true regardless of the diameter of the rim. Recent cars have much bigger overall diameter than cars of the '90s so they tend to have bigger rim diameters but the tire height that works best for them has not changed, it's still pretty much the same rule of thumb as indicated above.

The primary reason for this is that the stiffness, modes and frequencies associated with the tire change a lot with the height of the sidewall. The suspension needs to have matching characteristics. Otherwise what happens is a very non linear feeling, where the tire will be overpowered or underpowered and the car will react in a non uniform manner, for example a strong initial jerk from the tire followed by a much slower roll of the car, leading typically to having to correct the steering input long after the initial input. And of course the same will happen with the comfort aspects, the tire will work against the damping of the suspension or only one of the elements will do the work.

Also do realize that load carrying capacity is a function of how much air there is in the tire (i.e. higher sidewalk will make the tire able to carry more at same pressure, or to lower the pressure at same load, providing a better ride); and high speed capability is a combination of all of these and will be lower with an overloaded tire (i.e. if you don't take weight off your car as you stiffen it and put lower sidewalls you'll need to increase the tire pressure, hence further stiffening the tire, requiring even harder suspension, and having a tough ride).

I tested (both at Michelin and with BMW Motorsport) a range of wheel diameters on cars such as the E34 M5 and others and the technical guys and drivers always agreed on these results. The best mount we ever had on these cars was 235/45R17 all around (by the way, the other fad of mounting bigger tires in the back is another common misconception I will write about in the future if there is interest).

Of course that's when the marketing people came in and said we need bigger wheels, and also wider tires in the back... but everybody knew that when we departed from these optimal values, customers would pay more for a lesser result.

There is way more subtlety here (such as, what rim width to mount the tires on, depending on their aspect ratio; how tire measurement is done and on which rim width affects a lot of the characteristics of the tire (as an example, did you know that a 225/50-16 tire is not narrower than a 235/45R17 one by standard?). If there's interest, I'll try and write more.
It made a lot of sense to me as it sort-off chimed with what I have experience by trial and (many) errors when playing with wheel/tyre combos over the years on cars from my comparably modest powered Seven and to the Widow-making supercharged Monaro and crazy tuned 911 Turbo,,,. :)

OK, I admit that whilst I know he is probably right, I have ignored François' scepticism around the 'marketing fad' of staggered rears. However, if you look at his other posts he talks about there being minimal grip increase for the extra cost and increased rolling resistance and of course you cannot rotate fronts to rears, as noted by Brucey and others above in this thread....

However, my main concern was to keep the standard looks whilst moving to 'normal' wheel / tyres without any significant impact upon steering, comfort and feel at the wheel. Back to back measuring and comparing with the originals, I find the rear 265/40s are actually a slightly higher sidewall than 415 BBS / 240/45 TRX M635CSI setup, although not enough to make any significant gearing / speedo differences. So the rear passenger comfort levels should (in theory) be similar and as the rears do not affect steering feel or geometry, I will take the hit on tyre rotation over the improved stance of noticeably wider rear tyres (yes, it is people like me that the marketers target...)

Oh, and on the subject of weight: My (rather unscientific) initial comparison by lifting the 415mm/240-TRS front BBS then the 17"/245-Sportmax? They don't feel much different. If I get a chance this weekend I will do some proper comparison measurements of weight, sidewall height, Strut clearance etc and post some pictures.

Cheers,
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Re: Opinions on these wheels, please?

Post by Brucey »

one thing that I would note is that because the rim lips are different heights, the nominal sidewall height of TRX tyre and an inch size tyre can be 'the same' but the actual working sidewall height (i.e. the bit that can flex) is actually different.

The other thing I'd note is that if you stiffen the bushes in the suspension, and drive 'enthusiastically' eg on a track, you might want/tolerate tyres with stiffer sidewalls. IIRC E34 M5 (potentially a much heavier car at the rear end BTW) used roller bearings in the rear suspension which stiffened everything up laterally, and E24 M6 did not. Thus 235/45-17 is probably at least as stiff in the sidewall as you would need to go with any standard E24 chassis, IMHO.

The tyres I used on my staggered M-paras cost about £200 a corner. To discover that they actually lasted about 1/3 the distance they could have ( had I been able to rotate them) was 'something of a disappointment' to say the least.

If you want to fill your rear arches better, you can always use a hubcentric spacer.... BTW the rear track is wider than the front anyway, and accentuating this further doesn't seem to cause any big problems.

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