[zashata]

Hello all,
I have recently bought myself a wonderful bmw 320cd, from 2005. One which I have wanted for a long time, but the owned did not wanted to sell it to me. It has a lot of extras, has run only 110 tkm and looks fantastic. Probably the once that is missing is the M-package, but it is still very beatuful in my eyes It was sold to me with M135 18 inch rims with front tyres 225/40 and rear 255/35.

After I have gathered some experience with the car (this is my first bmw ), I need to ask for your opinion. I have some doubts about the ride. It is rather hard for me. I know that all coupes do come with sport suspension and that all bmw-s have pretty hard suspension when compared to others (owned an Audi before). However I do not know if moving to 17 inch (styling 119) with 225/45 tyres will significantly improve the ride. A freind of mine who owns 320d (with M suspension) says that 18 inch is twice as hard as 17 inch (which I really doubt, it is only ~1cm difference in the height). Does anyone have any experience with coupes and 17 vs 18 inch rims? I really do not want to get rid of the 18s, but the car has to be practical as well and driving through the city much rougher than the autobahn

Greetings from Germany,
zashkata

 

[Zell]

Smaller rims will increase ride quality due to higher profile tires. The general rule is the lower the profile of the tires, the more you're going to feel the road.

 

[Marshmallow]

Your suspension is likely trash right now. That is the majority of your problem. A smaller wheel is more comfortable but won't do much with the suspension being in bad shape.

 

[zashata]

I would not say that I have problems with the suspension. The car has been recently checked in the garage and everything that needed change has been immediately replaced. I never keep my cars in bad shape, rather the opposite

 

[k20z1 L]

I would not say that I have problems with the suspension. The car has been recently checked in the garage and everything that needed change has been immediately replaced. I never keep my cars in bad shape, rather the opposite

If your suspension is in good working order, maybe the BMW ride just isn't for you? Like said, it's definitely not as easy of a ride when compared to other cars. Different tire/wheel combinations will not make a night/day change, at least not in my experience.

If the ride is really rough, you may want to take another look at your suspension. Report back and hopefully we can help.

 

[Yewzer B Lewzer]

... says that 18 inch is twice as hard as 17 inch (which I really doubt, it is only ~1cm difference in the height).

It is sidewall height not overall height that affects ride quality, so the difference is significant (~24mm)

Edit: just did the research and you are correct, 11.5mm

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[generalvp]

I went from my factory 18" run-flat tires to 17" winter tires and noticed only a slight difference in comfort only. The suspension is stiff to begin with so the roughness will still be there, just not as much regardless of what tires and size you put on.

 

[330ism]

I'm pretty sure your shocks and stryts are not at 100%. Maybe replacing them coupled with bigger profile tires might help a bit but with sport suspension you'll still feel the road. That's the purpose I would presume.


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[k20z1 L]

I'm pretty sure your shocks and stryts are not at 100%. Maybe replacing them coupled with bigger profile tires might help a bit but with sport suspension you'll still feel the road. That's the purpose I would presume.


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+1 that is the purpose...

I would suggest getting under the car yourself and see what shape your suspension is in. If your suspension is in ok shape, you probably just don't enjoy our car's feel.

 

[zashata]

Guys, thank you for your responses!

I will have to check the car in 2tkm anyway (scheduled check), but as I said I doubt that the suspension is ruined. Quite on the opposite, It feels very stiff, solid and curves are just fun. The performance on the autobahn is perfect, and with speed 160-180 km/h you start to praise the suspension.

I assume that I have a "head issue" and simply I need to relax and get used to it. Probably I have to accept the ride and then I can enjoy it

 

[k20z1 L]

Guys, thank you for your responses!

I will have to check the car in 2tkm anyway (scheduled check), but as I said I doubt that the suspension is ruined. Quite on the opposite, It feels very stiff, solid and curves are just fun. The performance on the autobahn is perfect, and with speed 160-180 km/h you start to praise the suspension.

I assume that I have a "head issue" and simply I need to relax and get used to it. Probably I have to accept the ride and then I can enjoy it

Could very well be it. BMW's usually take a lot of getting used it.

Best of luck :thumbup:

 

[peytonracer4]

Is it a bumpy ride or a stiff ride? Sensitivity to bumps is a sign that the shocks are degrading. They can not be tested on the car. A shock does not need to be failed or leaking to perform bad.

To answer your question about wheels, when going from my 18s to 17s there is a difference but I really have to be thinking about it to notice it. If I'm not, I don't notice it.
When I go to my 16" winter wheels I do notice a difference. Fairly large. But that's mainly due to the fact that the winter tires themselves are extremely soft.

Maybe you should try out a different tire next time. Not all tires and created equal in comfort. Check tire racks website for specs and opinions on tires.
And don't ever use run flats. If you are, THAT is the reason for your awful ride.
My dad has a newer bmw with run flats and the ride was god awful. Seriously awful. Felt like there were no shocks or springs and it was just direct contact to the road.

We recently switched them out for some stiff, but non run flat tires. It is absolutely more comfortable. It doesn't feel like your back is going to break over every mark on the road. Nothing else was changed but tires.


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[k20z1 L]

Is it a bumpy ride or a stiff ride? Sensitivity to bumps is a sign that the shocks are degrading. They can not be tested on the car. A shock does not need to be failed or leaking to perform bad.

Just wanted to clarify this - sensitivity to bumps could be a sign of multiple worn parts. It would be best for you to diagnose your car before jumping to any conclusions. Always could be something inexpensive that's bothering you.

 

[mjpgolf1]

Check tire pressures also. They may be on the high side and You may be able to bring the pressure down a bit and soften things up enough that you can live with it.


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[lszlszx]

17" would make ride a little softer, but I'm not sure if it's worth buying a new set of wheels for that. The sports suspension is quite stiff, even with 17" rims.

 

[Alex323Ci]

Agreed on many things stated. I was going to post these same things but fanatics already posted.
18 to 17 could help a little, but the tire's sidewall stiffness is what makes that difference. Lower profile tires are "usually" firmer sidewall material, but different brands and model tires change between moderate to really firm in sidewall makeup. So just a tire model change alone could help your situation. And stay away from runflats!

Check your tire pressure, some run 40+ psi where 30-35 psi is fine for many tires.

 

[zashata]

Guys, I have one other question: if I decide to switch to 17, which one would you recommend - I might have on my wish list either Styling M68 (front 225/45 and rear 245/40) or styling 119 with allaround 225/45. I could say that m68 looks a little bit "older" in design, but having bigger tyre in the back looks rather good.
On the other hand, styling 119 looks very stylish in my eyes but I am not sure if it is "unsafe" to have the same size tires on all 4 wheels. Some "specialists" mention that a BMW should always have bigger rear tyres. But I think that 225 allaraound will be also ok.

Anyone experience / opinion?

Thanks!

 

[compcrasher86]

Guys, I have one other question: if I decide to switch to 17, which one would you recommend - I might have on my wish list either Styling M68 (front 225/45 and rear 245/40) or styling 119 with allaround 225/45. I could say that m68 looks a little bit "older" in design, but having bigger tyre in the back looks rather good.
On the other hand, styling 119 looks very stylish in my eyes but I am not sure if it is "unsafe" to have the same size tires on all 4 wheels. Some "specialists" mention that a BMW should always have bigger rear tyres. But I think that 225 allaraound will be also ok.

Anyone experience / opinion?

Thanks!

My E46 has sport suspension and non-staggered Style 68 wheels and I can assure you that it drives safe and is plenty enjoyable to drive. Mine won't break them loose in everyday spirited driving unless you are doing something silly with it. Am I advocating for non-staggered? No, but I wouldn't consider it unsafe.


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[SupaDupa Steve]

Plenty of BMW's even come with non staggered fitment. I wouldn't recommend running the same size tires on staggered wheels though

 

[[email protected]]

I went from 17s to 18s.p, in the sizes you are talking about. I choose continents extreme contact DW tires and the ride is not any harsher than with the 17s.

I would suspect runflats is your problem, they are very stiff and affect ride quality. Check your tires