Wheels and Tires VS. Ride Quality

[kouks]

^ Now I'm completely confused.

But really, I expected a wide range of opinions, since ride is a very subjective item, we each like our own comfort area, and we all have different driving styles. One man's trash is another treasure, as the saying goes.

As an engineer I asked this question to get opinions on brand names and how they actually perform in the car.

I like this thread because it combines opinions on the suspension springs and shocks, but also covers probably the biggest part of the system, the tire and wheel sizes. For instance, the M5 SLS delete setup I now have on the car drives great, no harsh ride and very little roll, in fact took a 90 deg highway on ramp with the kids in the car today at about 50mph and the kids about lost it, but the car turned great with a little bit of roll. Now this is with the 15" wheels and a 205/60 tire. This tire size applies forces to the spring/damper system gradually since the tire takes the initial force input and compresses well. If you go to a 17" wheel with 40 or 45 sidewalls, the force input would be more rapid. The spring would try to compress and reduce the impact, but the M5 springs don't have a good rate to do that, so the impact will transfer to the chassis. The damper just reduces the amount of bounce, but the rate it also compresses can increase/reduce impact to chassis.

If you have Sport springs, with HD shocks, 40 size tires = moderate impact on the system, spring transfers impact without compressing fast, shock allows transfer of impact by not compressing and not allowing any bounce. (Harsh ride)

If you have Sport springs, standard shocks, and 40 tires = same as above, but shock will allow spring to compress some more, less transfer of impact to chassis (Sport ride)

If you have Sport springs, standard shocks, and 60 tires = low impact due to tires, spring transfers low impact, but shock compresses to slow transfer of impact (Moderate ride)

If you have standard springs, standard shocks, and 60 tires = low impact from tires, spring partially transfers impact, shock compresses to reduce impact further (Grandpa smooth ride)

You can move around each component all you like and get your own setup scenario.

As an example, my e38 740iL came with standard suspension and fat tires. Rode like a marshmellow (old grandpa Cadillac) for me, others like that ride. First I put on Sport springs. It got a bit better, but still too marshmellow. Then went to 18" MPars and 50 tires front, 40 back, rides much better. The lower profile tires gave the suspension the correct amount of impact to make the car feel responsive and were also helpful during turns with less sidewall deformation. Others go to coilovers or Billy HDs, but that would be too tight for me. What I have is tight enough for me.

Although most people hate the BavAuto springs, I can see where dgz32 likes them. He is on 50 tires that take the initial impact well and do not transfer the full impact to the springs. This makes the system behave a little tighter than an OE ride, but still some sportiness. Most others drive with the 40 or 45 tires, which transfer more impact to the spring. Since BavAuto springs are the same rate as OE they compress faster than Sport springs and because they are shorter, can bottom out. Thus those with more aggressive wheel/tire setups don't like them.

The other issue is bottoming out on lower and lower setups. I considered the LowTec 60/40 setup and actually found a set, but there are mechanical issues with driving that low and I don't think it would work well as my daughters DD. Sure would look good though.

So to avoid the harsh ride, but stay sporty, I think the road I will take is H&R springs (sporty but not as tight as the M5 springs), 40 or 45 tires (better response in turns, some impact transfer), standard shocks (compress to slow the impact from the 40 tires and sporty springs).

[sugaki]

As an engineer I asked this question to get opinions on brand names and how they actually perform in the car.

<snip>
If you have Sport springs, with HD shocks, 40 size tires = moderate impact on the system, spring transfers impact without compressing fast, shock allows transfer of impact by not compressing and not allowing any bounce. (Harsh ride)

If you have Sport springs, standard shocks, and 40 tires = same as above, but shock will allow spring to compress some more, less transfer of impact to chassis (Sport ride)

If you have Sport springs, standard shocks, and 60 tires = low impact due to tires, spring transfers low impact, but shock compresses to slow transfer of impact (Moderate ride)

If you have standard springs, standard shocks, and 60 tires = low impact from tires, spring partially transfers impact, shock compresses to reduce impact further (Grandpa smooth ride)

Talking strictly about shocks, comfort and sportiness aren't mutually exclusive with suspension. You can have a sporty ride and comfortable ride (digressive shock valving). You can conversely have a mushy ride but feel harsh at the same time (progressive shocks). It's because shock compression/rebound isn't necessarily linear. A shock can compress more with the small bumps, but resist compression more over larger bumps--that's digressive and more desirable for daily driving.

I'm guessing Bilsteins have linear valving, because to me it's not very good at absorbing the high-speed bumps (ie the small road imperfections). Subjectivity of ride quality also has to do with the smoothness of your roads. It seems like Bilsteins were made for the track, because on poorly maintained roads in California I feel every rut. Handles amazing and it's much more capable than the Koni, but Koni's feel more digressive in the shock valving. Since I value ride refinement viewing my E34 as a luxury sports sedan I prefer Koni.

Complicating things more, shock valving should match the spring rate of your springs, sway bar stiffness, etc.

[SWS911]

My 535 manual is sporting 8 & 9 x 18 style 32 with Bridgestone Potenza S-04 225/40 fronts & 255/35 rears. H&R sport springs with Bilstein Sports all the way around and M5 sways front and rear. This car handles great and is fun to drive, but you grimace when you see a slight divot or pebble in the road. I can drive my sons E46 325 manual sport coupe with stock sport suspension, staggered 7.5 & 8.5 x 17 with Yokahamas much faster and rides so much smoother then my E34. I just have to remember to turn that stupid traction control OFF when I get into it. My DD is an E36 318ti auto with square 7 x 16 205/55 whatever tires and stock suspension. It works! I think the best compromise is the 45 ratio 17" tires with factory sport springs and shocks, or comps, with M sways. My .02

[GregT53]

@kouks You have made as reasoned a decision as possible given the variability of components, component mixes, and the generally subjective nature of this kind of modification. This has been a valuable thread, especially the discussion on valving, so I am hopeful the moderators park it somewhere in the archives that is easily accessed.

Let us know how things work out.

[kouks]

I think this thread is the perfect companion to the current thread:

https://www.bimmerforums.com/forum/s...4-Spring-Table

And the updated version:

https://www.bimmerforums.com/forum/s...(new-for-2012)

No data on M5 front spring though. Anyone have numbers on those?

[kouks]

OK, deleted the M5 Delete setup and installed Vogtland springs. The car has dropped nicely, only about an inch of space between the fender and the front tires (pics soon).

Initial drive was only about a mile near the house, but drove very nicely, no harshness, even going over a washboard type road near us. This is on standard 205/65/15 tires. Soon I'll be swapping to 235/45/17 and we'll see what that does. Right now I am impressed with the ride quality. Stiffer than standard, but only slightly. The Vogtland are measured at only 10% stiffer than standard and thats pretty much how they rode. Smooth yet poised. Actually felt close to my e38 on sport springs and staggered 18" MPARS. I'll update as I drive it more.

[kouks]

[Mixzzz]

What shocks did you use? And how is the ride quality? I think I'm going with Eibach, but Vogtlands are cheaper so not so sure which ones to take. Also post a pic when you put on the style 32s. Im restoring e34 right now and I'm thinking about style 32 18x8 and 18x8.5 or 9 in the rear. They're not so common in the r18 size though

[kouks]

Photo on Vogtland springs, standard shocks (Gabriel) and standard 205/65/15 tires on 15" wheels

Untitled by Bill Koukourikos, on Flickr

Really nice forward rake and very smooth ride, almost OEM. I personally love the stance. I was able to get a Volvo lip too, but I think that will be too low to be good for a DD. I'll try it for a while.

[kouks]

What shocks did you use? And how is the ride quality? I think I'm going with Eibach, but Vogtlands are cheaper so not so sure which ones to take. Also post a pic when you put on the style 32s. Im restoring e34 right now and I'm thinking about style 32 18x8 and 18x8.5 or 9 in the rear. They're not so common in the r18 size though

From what I've read here by multiple people, going up to 18" wheels may look great, but the ride quality will really suffer. The e34 is a pretty light car and the big wheels will not create a great ride experience.

[BleedsBlue]

Well, that looks good now Bill. Sorry the M5 springs didn't work out

Someone with an S38 in the nose can still use em.

[ross1]

From what I've read here by multiple people, going up to 18" wheels may look great, but the ride quality will really suffer. The e34 is a pretty light car and the big wheels will not create a great ride experience.

Yep, had 18s on a car I bought a while back. Couldn't get 'em off fast enough.

[kouks]

Well, that looks good now Bill. Sorry the M5 springs didn't work out

Someone with an S38 in the nose can still use em.

No problem. I had my suspicions from the start if they would actually drop the car. Additionally, the new setup has completely new front end parts, so no idea if that affected things. Even before the M5 spring install, the car vibrated at 50-55mph so some control arm was going bad to begin with. Smooth as silk now. I'll be posting the M5 springs for sale in the forum soon.

What has surprised me is the cost of suspension work. I think the engine rebuild was cheaper. By the time new tires and style 32 wheels are installed it may be around $2k just for suspension.

[BleedsBlue]

No problem. I had my suspicions from the start if they would actually drop the car. Additionally, the new setup has completely new front end parts, so no idea if that affected things. Even before the M5 spring install, the car vibrated at 50-55mph so some control arm was going bad to begin with. Smooth as silk now. I'll be posting the M5 springs for sale in the forum soon.

What has surprised me is the cost of suspension work. I think the engine rebuild was cheaper. By the time new tires and style 32 wheels are installed it may be around $2k just for suspension.

Good to know.

Re: the cost. I know! It's crazy. That's why I always ask about suspension when people post potential E34 purchases, talk values, etc. It is easily $2k to get one properly sorted with lasting rubber parts and ball joints (Lemforder or better), shocks, etc. It pays off when you're done but there is so much rubber and potential slop/play...

[kouks]

[IMG]Untitled by Bill Koukourikos, on Flickr[/IMG]

Style 32 17 in wheels with 235/45/17 tires (Delinte off brand). Drove it for about an hour on all types of roads around town after the new shoes were installed and it was a great ride. Did not lose too much of the soft ride from the 15 in wheels and gained better cornering due to the thinner sidewalls. Drove over a pretty bad road nearby and it performed about like my e38, although this is a lighter car and bounced a little more, but not anything significantly different. I personally love the ride and the look, very happy with the results. Based on the feel, I could have easily gone to a staggered 17x9 rear wheels and 245 tires and most likely would not have lost much on the ride. I think the Vogtland springs and standard shocks is a good combination and works well together. Need BMW wheel caps.

Stats:

1995 525i, M50 engine
Vogtland Springs
Standard shocks (Gabriel)
OE Style 32 17x8 wheels
Delinte 235/45/17 tires square setup.

Thanks to all who offered advice on this, hopefully others will learn from the reading.

[tantumaude]

Spent a while perusing this thread. Settled on a combination of Eibach springs and Koni yellows for my 540i/6. I run 18" Mpars with 40s up front, 35s rear. I drive mainly highway, but have a lot of bad roads around me as well. Will report back as soon as they're installed.

[kouks]

Spent a while perusing this thread. Settled on a combination of Eibach springs and Koni yellows for my 540i/6. I run 18" Mpars with 40s up front, 35s rear. I drive mainly highway, but have a lot of bad roads around me as well. Will report back as soon as they're installed.

I think the 18" MPars may create a harsh ride. This is just from what I've read. They do look great on these cars though.

As fun as the M50 is in this little car, I'd love to have a M60 in it, bet its a kick in the pants.

[cirrusblau]

Spent a while perusing this thread. Settled on a combination of Eibach springs and Koni yellows for my 540i/6. I run 18" Mpars with 40s up front, 35s rear. I drive mainly highway, but have a lot of bad roads around me as well. Will report back as soon as they're installed.

I have this exact combo, exact tire size, exact wheels except on a 535i. I have the Konis set on full soft both front and rear, and they ride nice. Firm but not jarring or uncomfortable. Not harsh at all.

[tantumaude]

I have this exact combo, exact tire size, exact wheels except on a 535i. I have the Konis set on full soft both front and rear, and they ride nice. Firm but not jarring or uncomfortable. Not harsh at all.

Excellent, that's exactly what I'm looking for. This is a DD, but I'd like it to handle more like my other sports cars.

@kouks: It's pretty good, but it really needs the 3.15LSD I've got sitting on my workbench. Coming from a 3.15 equipped manual-swapped E39 540, this one needs to really rev up before it starts to fly. I've got several wheel sets in 17 and 18, the Mpars are my favourite. Running 17" style 5s in winter.

[BleedsBlue]

I don't know anything about Delinte tires, but not enough credit is given to the tire in the 16 vs 17 vs 18" wheel debate. Cheap or track-biased tires on M Parallels are no fun, but get something with proper road-biased sidewalls (Michelin, Goodyear F1, even Conti DW [not DWS]) and 18s are not as bad. It's all anecdotal of course.

[kouks]

I don't know anything about Delinte tires, but not enough credit is given to the tire in the 16 vs 17 vs 18" wheel debate. Cheap or track-biased tires on M Parallels are no fun, but get something with proper road-biased sidewalls (Michelin, Goodyear F1, even Conti DW [not DWS]) and 18s are not as bad. It's all anecdotal of course.

Earlier in this thread there is a discussion on tire quality. I personally love Michelins, especially the touring tires, but cost is always a factor. Conti DWS were also fantastic on the e38...quiet and smooooth. My other daughter has DWS on her e46 325Ci vert and they are also smooooth.

Like all questions and decisions in life, the answer is always...it depends.

If I were going to be an aggressive driver, the tire quality would play a bigger role in the decision, but for my daughter driving around town and to school they are fine.

Not sure if the Delinte brand is sold outside of CA, but have seen it around here and one of the forum members on the e38 side has a tire shop in San Diego and has good stuff to say about them. They are off brand and inexpensive. The tread is not directional so good for rotating all the tires, and is an all weather tread (well, for California at least). My fronts on the e38 are Delinte for about 10,000 miles so far and feel fine. I was trying to decide between Hankook V2 and the Delinte and even the local tire shop I frequent told me the only difference in around town driving between the two would be tire wear (Hankook last a bit longer). So I went with the less expensive brand. I have no complaints about the ride. The former /65 tires were Michelin, and the /45 Delinte feel almost like them.

One thing I have noticed in the lower stance, the car will not compress much when I sit on the fender and try to bounce it. The Vogtland springs are only supposed to be about 10% stiffer than OE, but I think compressing the struts the extra inch puts the shocks in the stiffer valve range and they do not move as much (just guessing here). This has not degraded the ride quality though. When the OE M5 springs were installed I could bounce the car more easily, the shocks allowed more travel since there was little compression on my chassis. That may have caused the harsh ride on the washboard type roads if the shock allowed to much movement.

[tantumaude]

I have this exact combo, exact tire size, exact wheels except on a 535i. I have the Konis set on full soft both front and rear, and they ride nice. Firm but not jarring or uncomfortable. Not harsh at all.

I've driven about 600 kms since installing this. The ride is a lot tighter, but I have to say also a lot harsher than I expected--I drive daily on a couple of really bad roads around my house, and I notice every rut and bump. Not sure how long I'll stick with this setup to be honest. I think the shocks are fine, just need softer springs.

[katit2]

Reading this topic with mixed feelings I just did suspension rebuild with all stock components and that stance... Those 15 wheels. Front sitting higher.. Just killing me I feel like I want to drop it, put wider 17 wheels on it and tint. But I don't want to compromise ANY comfort. But that granma look.. Practicality of current setup is like 150%. I can take car to woods hunting/fishing. Don't worry about parking, don't worry about curb rush on wheels. Cheap tires, etc.. But that look..

[fo3]

Reading this topic with mixed feelings I just did suspension rebuild with all stock components and that stance... Those 15 wheels. Front sitting higher.. Just killing me I feel like I want to drop it, put wider 17 wheels on it and tint. But I don't want to compromise ANY comfort. But that granma look.. Practicality of current setup is like 150%. I can take car to woods hunting/fishing. Don't worry about parking, don't worry about curb rush on wheels. Cheap tires, etc.. But that look..

Found this old thread while searching for tire recommendations. But laughing at those comments.
A good compromise is what I have, BMW 16" rims and 225/55 profile tires. My tires (tyres) are gone though and I need to find some good brands at a decent price in my size, or cross shop some other size (wider/narrower and different profile) to make the same rolling diameter. I don't really want the firmer ride from 50s, but 60s get a little too high in the sidewall.
At the end of the day I'm going to have to go to a common size/profile to get a decent deal though. I hate oddball sizes. E: I just realised my 16" rims were from a e39 and 225/55/r16 were the standard size for them anyway.

[blackdog]

This thread is very useful for me as I want to upgrade wheels and tires on my '94 525i. I initially wanted M-Pars but this has convinced to probably going with a 16" setup. I am almost 52 years old and not looking to drift or be a tuner boi, hahaha. Now if anyone has some wheels and tires for sale.....