[Kieran97]

Hi Guys,

Long time reader, first time poster. I test drove a 2017 330d at the weekend, m sport, 19 inch rims. A lovely car, bags of power (massive step up from my Ford Focus!)

Anyways, after the test drive, the only thing that bothered me was that on rough UK back roads at least, every bump at low speeds was like a shock up my spine. It was a particularly rough road we took part of the test drive on, and I did expect it to be firm being an M sport model, but not that firm. I cover a lot of mileage for work, travel a lot, so I value comfort but still would like a car that's relatively fun to drive.

My own thoughts having done a bit of reading is that it's the run flats. I wouldn't mind carrying a space saver wheel in the boot, i'm a single male aged 25, not usually carrying a lot of stuff around.

Will a set of non run flats make a night and day difference, or is this just not the car for me?

Kieran.

[cfm56d7b]

Switching to non run flat tires will make a noticeable difference. The definition of night and day would be entirely up to the driver.

How many miles does the vehicle have at the moment? What is the state of the suspension?

How many miles are on the current se of tires (if they are in fact run flat tires)?

As run flat tires wear out, the amount of tire compound between the road and reinforced sidewall is reduced. As a result, road imperfections are felt more and more.

Brand new run flat tires and run flat tires with 7K miles will feel completely differently.

If you really like the car, switching to 18" wheels (which clear M Sport brakes if the vehicle has these brakes) may be yet another option.

[Kieran97]

Originally Posted by cfm56d7b

Switching to non run flat tires will make a noticeable difference. The definition of night and day would be entirely up to the driver.

How many miles does the vehicle have at the moment? What is the state of the suspension?

How many miles are on the current se of tires (if they are in fact run flat tires)?

As run flat tires wear out, the amount of tire compound between the road and reinforced sidewall is reduced. As a result, road imperfections are felt more and more.

Brand new run flat tires and run flat tires with 7K miles will feel completely differently.

If you really like the car, switching to 18" wheels (which clear M Sport brakes if the vehicle has these brakes) may be yet another option.

First off, thanks for the response.

There are 48k miles on the car, its 2017, so suspension should be fairly good. 19 inch rims, with run flats. Tyre condition looks good, but not brand new.

It has m sport brakes, so 18 inch would be an option. The one piece of advice I seem to have got from friends with 3 series/5 series generally is to ditch the run flats.

In no major hurry to change and will test drive a few more before I commit. Seen a very nice 430d with adaptive suspension advertised. Maybe the adaptive suspension could help.

Found it ok on good road, back roads just felt every bump up my spine at low speeds and it out me off as I do a lot of driving with work.

[StealthF32]

I can attest to the noticeable difference, as I just recently made the switch from run-flats to non run-flats....there's no going back for me - - if you're worried about getting a flat, just get roadside assistance coverage or simply call a tow truck should the situation arise....

[Watsey]

Switching from RFT to non-RFT makes a significant difference.

Switching to ultra high performance non-RFT makes an even bigger difference, if you value grip/traction/handling as well as ride quality.

Just have an 'instant' puncture repair kit in the boot, or tyre sealant, or an inflator (I have all three) and you'll be able to repair the tyre in the event of a screw or nail.

Nothing will save you from serious damage in the event of hitting a big pothole (i.e. the rim cutting through the tyre carcass) but I've only had that happen once in 37 years of driving.

[cfm56d7b]

Originally Posted by Kieran97

First off, thanks for the response.

There are 48k miles on the car, its 2017, so suspension should be fairly good. 19 inch rims, with run flats. Tyre condition looks good, but not brand new.

It has m sport brakes, so 18 inch would be an option. The one piece of advice I seem to have got from friends with 3 series/5 series generally is to ditch the run flats.

In no major hurry to change and will test drive a few more before I commit. Seen a very nice 430d with adaptive suspension advertised. Maybe the adaptive suspension could help.

Found it ok on good road, back roads just felt every bump up my spine at low speeds and it out me off as I do a lot of driving with work.

Switching to run flat tires and 18" wheels will definitely improve comfort. BMW OEM 400M 18" wheels + non run flat tires may be the most practical solution (cost not being a factor).

My vehicle has M Adaptive suspension. There are two main settings: Comfort and Sport. Neither setting corrects what is best describes as a lethargic compression and rebound response of OEM M Adaptive shocks. The vehicle tends to bounce as the shocks eventually fail to rapidly adjust to increasing road imperfections.

In an ideal scenario: the shocks rapidly compress and rapidly rebound to maintain suspension geometry and tire contact with the road. That's not the case with M Adaptive suspension. I still feel it has value but the value is limited, at least IMHO.

Comfort is a very subjective perception but the major components of comfort are:

- Suspension travel; one of the biggest contributors
- Front and rear spring rates
- Shocks design: compression and rebound (as mentioned above)
- Unsprung weight (heavy wheels add to unsprung weight)
- Wheel size and weight
- Tires: RFT vs non run flat

[danb1979]

Originally Posted by Kieran97

Hi Guys,

Long time reader, first time poster. I test drove a 2017 330d at the weekend, m sport, 19 inch rims. A lovely car, bags of power (massive step up from my Ford Focus!)

Anyways, after the test drive, the only thing that bothered me was that on rough UK back roads at least, every bump at low speeds was like a shock up my spine. It was a particularly rough road we took part of the test drive on, and I did expect it to be firm being an M sport model, but not that firm. I cover a lot of mileage for work, travel a lot, so I value comfort but still would like a car that's relatively fun to drive.

My own thoughts having done a bit of reading is that it's the run flats. I wouldn't mind carrying a space saver wheel in the boot, i'm a single male aged 25, not usually carrying a lot of stuff around.

Will a set of non run flats make a night and day difference, or is this just not the car for me?

Kieran.

Fellow UK F3x owner here pal... Albeit an F31 325D M Sport touring

I binned the 19" 403Ms with Bridgestone RFTs as soon as I got the car; fitted OEM Style 400Ms with 18" RFT winter tyres all round and now running 18" Style 405Ms with non RFT Goodyear Assym6s all round and the car drives & handles superbly

The 19s look great; but the car drove horribly and it was the best thing I did binning them...

I knew after the test drives they'd be going!

I do keep considering 19s and if I go down that route they'll be one one size wider non RFTs - better rim protection, straighter sidewall and IMO that's what offers a better ride, handling and turn in etc...

[ssf556]

Originally Posted by danb1979

Fellow UK F3x owner here pal... Albeit an F31 325D M Sport touring

I binned the 19" 403Ms with Bridgestone RFTs as soon as I got the car; fitted OEM Style 400Ms with 18" RFT winter tyres all round and now running 18" Style 405Ms with non RFT Goodyear Assym6s all round and the car drives & handles superbly

The 19s look great; but the car drove horribly and it was the best thing I did binning them...

I knew after the test drives they'd be going!

I do keep considering 19s and if I go down that route they'll be one one size wider non RFTs - better rim protection, straighter sidewall and IMO that's what offers a better ride, handling and turn in etc...

Nice looking car!

[JeffSmith]

My wife had runflats on her Mini cooper, and the ride was awful. However i dislike driving without a spare wheel, and will be looking closely at the 320D Touring i have just purchased to see if a spacesaver could be stored under the load area floor. I previously owned a Mercedes E-class estate, and that was also supplied without a spare. Mercedes and the owners club told me it was impossible to fit one under the load area. However after a lot of measuring, and moving one of the batteries slightly, I did manage it, and it gave me great peace of mind on long journeys. Has anyone managed the same trick on a 2016, 320 Touring?

[johnung]

MODDING FOR COMFORT & SPORTINESS

When we first got our F30 335i XDrive 5+ years ago, I loved the sporty handling and XDrive but absolutely hated the lack of ride comfort. Even on the highway, it was jolting hitting road seams. Definitely wasn’t an enjoyable car to take on a day trip.

My wife had work cars during that time that we took for those types of drives, first a Lexus that was comfortable but floaty and definitely not a sporty driver. And later it was replaced by a Mercedes E-Series 4-Matic that was firm not floaty, but comfortable. I’d call it stoicly sporty, but not the sheer fun of the BMW XDrive. Great comfortable ride for a trip.

So those two cars were my basis for comparison of what Comfort meant on a long trip. As Covid changed work and travel we needed a single car that we could share for daily driving and for trips. Neither of us would give up the joy of driving the BMW especially as I modded it more, first with my wife’s permission and later as I found asking for her forgiveness to be more effective.

So the F30 BMW would have to be modded for Sportiness AND Comfort. Here are the choices that I made and recommendations with those goals in mind.

1) Stick with 18” wheels. They are the sweetspot for the F30. The largest M Sport/M Performance Brakes fit under them. 18” sidewall heights provide the best ride and protection for both wheels and tires. Guys who switch to 19” wheels especially in areas with rough roads, complain much more about uncomfortable ride and increased tire & wheel damage. 20” seems to require local roads that are smooth as glass.

2) Ditch stock runflat tires. When I did I’d estimate that their stiff sidewalls accounted for about half of the original stiff/jolting ride.

3) Choose a comfortable tire, but obviously don’t sacrifice performance. After all they are going on a freakin BMW! There are distinct differences between tire models.

My 3 best sources for tire information in no particular order are:

a) TireRack website ratings, reviews, specs

b) This YouTube channel:
https://youtube.com/@tyrereviews?si=s5Atlb_WyQ8_4N9x

c) Alohasurftoad Bimmerposts

TIP: Don’t Cheap Out On Tires!.
Besides performance and comfort, tires are a huge safety item for you, your family and anyone that they may save from personal tragedy. The couple hundred bucks that guys try to save on less desirable tires comes out to pennies per day for the 3-4 years of the best tire’s extra protection.

My Tire Choices:
I wanted to try the best summer tires for once in my life so I chose the Michelin Pilot Sport 4S. I wasn’t disappointed! Most phenomenal handling tires that I’ve ever had. Feels like the edges are actually gripping the asphalt entering curves. I was also incredibly impressed with his they handle rain, and how comfortable & quiet they are. They help to soak up highway seams and potholes. Make wet roads feel like dry. I have to remind myself to slow down.

If I was looking for all seasons I’d consider Continental DWS06+. My winter set is Michelin X-Ice SNOW. Absolutely amazing. Make driving on Black Ice seem like dry road.

4) Choose An Upgraded Tire Size
This will provide better handling and ride comfort. My car came stock with 225/45-18 Pirelli runflats over BMW 400M 18x8 ET34 wheels. I could have chosen 235/45-18 or 245/45-18, but I chose the best handling option of 245/40-18. This was the widest tire that would fit on the stock 8.0” wide wheel. And the non-runflat MPS4S tires increased both handling and comfort. The square setup allowed me to rotate tires front to rear which kept them beautifully even and at their highest performance for their full tire life.

I recently bought my second set of MPS4S, this time in 255/40-18 over square Forged APEX VS-5RS 18x8.5 ET40. This setup adheres to the principles that I described above and also reduces unsprung weight and more importantly Rotational Mass by 9.8 lbs per corner. (Stock 53.1 lbs vs 43.3 lbs measured on post office scale.) This large reduction in Rotational Mass means improved acceleration, improved braking, improved handling and even improved gas mileage..

5) Upgrade Dampers
Replace cheap stock front struts and rear shocks (unless your car comes with BMW Adaptive dampers) with Koni Special Actives. KoniSA’s have dual valve technology that Koni developed with McLaren so that respond to road conditions as both a Sport shock and as a Comfort shock. They improve handling and comfort significantly. Other damper brands/models will usually decrease comfort not improve it.

6) Lowering Springs (Optional)
Avoid springs with much higher spring rates like H&R and Dinan. They will make your ride more stiff/harsh. Eibach makes spring kits that are model specific to add more control and often reduce the BMW reverse rake with the larger front wheel tire/fender gap.

Note: If you install lowering springs it is important to trim the stock bump stops to take into account the estimated drop with the springs. (Usually top of bump stop is trimmed with a serrated knife like a 6” kitchen tomato knife.) This is especially true for the KoniSA’s. You don’t want shocks bottoming out on their bump stops prematurely because the chassis is a little lower.

7) Upgrade Rear Sway Bar (Optional)
Often people install much stiffer springs in an attempt to reduce body roll, but that degrades ride comfort. Sway bars directly affect body roll. The F30 front sway is expensive to replace because of the high labor to remove everything in the way. The rear bar is easier to upgrade. It reduces body roll and reduces understeer. It’s important to check realoem for a car’s stock rear sway bar diameter. Many are only 12mm. BMW makes a 15mm rear sway bar that is a direct replacement. Other companies also make rear sway bars in 16mm and 17mm. See photo.

8) Install A Front Strut Tower Brace
This reduces front chassis flex which to the driver makes steering feel quicker into turns. It’s an inexpensive do it yourself upgrade. Information below. Strut braces with removable crossbars are better because it’s easy to service engine without removing tower stretch bolts.

IMO best strut brace
https://www.kiesmotorsports.com/prod...e&_ss=r?aff=22

Strut Brace Installation Video
https://youtu.be/eP9Jyr2v93s?si=SPBtgFmo5Wr6UBYd

Hope this helps.

[Riks_g]

This threads been a great read.

Was thinking about changing my runflats to non runflats in the next few months and this has confirmed my decision!