[Posull78]

Looking for someone with std M sport suspension that might have moved from 20 to 19. Did it make a noticeable difference? Still finding my ride too firm after adjusting the tire pressure (tires were overinflated at delivery).

Trying to avoid moving to non run flats because I don’t have a spare. Can’t really do a tire kit, it’s my wife’s car.

Honestly pretty close to dumping the car … an expensive proposition considering the car only has 270 miles…

[Drothgeb]

We plan on running 19” winter tires but haven’t installed them yet. Do you have the Adaptive Suspension?

[Posull78]

No adaptive suspension on our m40i

[Drothgeb]

Without the adaptive suspension, non RFT tires are probably your best bet. Either 19” or even 18” for a little better ride. I test fitted 18”s with 245/60s on my wife’s M40i yesterday. She didn’t like the look, so we are going 19s with 255/50s instead.

As far as no spare for your wife. Blow-outs don’t happen often. Most flats start out as a small leaks that don’t get repaired. With the TPMS, it’s really easy to catch and have a leak repaired before it becomes a flat. And carrying a small 12v compressor to inflate a low tire until you can get it repaired is much easier than changing the spare. We’ve been carrying compressors in our cars for many years. Also have a can of Fix-a-flat or similar too. If you do have an actual blow-out, there’s always AAA.

[335dFan]

I don't meet a couple of your criteria for providing an answer, but since you asked. I have the OEM 245/50-19" RFT Bridgestone Alenza and have not had 20"; bought it 7 months ago and have a little more than 7k miles. Even with the RFT I have the spare tire option.

I have the Adaptive M Suspension. But I have driven it in all modes: Sport Plus, Sport, Comfort, and ECO. I came from a 2011 335d with 18" wheels and Michelin Comp4S non-RFT tires, and a heavily modified suspension.

I find the 19" OEM RFT tires to be quite cushy; even my wife does and she hated driving in the 335d. About the only time it is harsh is when I am in Sport Plus. The roads where I live aren't too bad, compared to downtown Philly for example, but there are some that are close to Philly.

Having said all this, I will likely get another set of wheels and keep the OEM wheels for snow tires and/or more all-terrain-like tires. The other set of wheels may be BBS 20" and I will try to find the best Michelin non-RFT performance tires I can find in a square setup, which is how I prefer my driving machine. I don't plan on using any larger than OEM tire sizes. Not my thing.

[Isawelvis]

Go to non run flats would be the cheapest and easiest if you stay with 20 inch. Also, look to Members classified. There are always people selling complete sets of tires and rims in 19 inch. Maybe you could work a swap out with someone. Many people want to go from 19 to 20 just for performance and looks. Currently I have the standard X3I with Non runlets and a factory spare. Really wonder why I ordered the spare because Im really to old to change a tire anymore. Guess I still think I have it but really I don't. I still carry a can of fix a flat even though I have the factory spare. Good luck. There are numerous options out there for you

[wdeerfield]

I have both 19s and 20s in run flats. But… I have adaptive suspension which makes a world of difference with run flats. With 19s you'll get more sidewall making it a little more comfortable and numb. It's noticeably smoother on highways with square 19s than my staggered summer 20s. You might be good with 19s ans run flats. I'm willing to bet members where will definitely trade with you for your 20s for their 19s

[MikeG12]

I went in the opposite direction, from 19" RF all seasons to 20" nonRF all seasons. The 20" are significantly better in handling. 19's felt very rubbery with no firm steering feel. The 20's are better in handling and riding comfort. I have adaptive but I don't think that makes much difference because I have driven cars without the adaptive.

[MdW86]

It depends on what you prefer. Personally I prefer the 19 over the 20, because I like a more comfortable ride. When driving with the 20 inch, it feels like i am driving in a 'sport comfort' mode. Therefore i prefer the 19, if i want to drive sporty, i'll activate sport mode (with adaptive). If you think 20 is to firm, a 19 inch set will most likely fix it. Perhaps your dealer has a demo you could try…

[Jen4BMW]

OP- For reference my DD is a 19’ GO1 xDrive30i with 19” RFT’s. In terms of ride comfort I’d say it just about hits the sweet spot between firmness and comfort. Sport mode makes a significant difference. Unless I am hustling, it’s not an enjoyable ride for everyday use. Sport transmits every little road imperfection. Some like this. I for one do not for everyday.

For comparison sake, I recently had a 20’ M40i loaner with 20” RFT’s. The ride with M adaptive selected felt almost as firm as my DD in sport mode. At best maybe 15% softer. I am still on the fence as to whether the power upgrade justifies the stiffer ride in the M40i with M adaptive. But oh man that POWER

I think 20” non RFT’s would move you into comfort territory on your DD.
I’ve also driven a 30i with Non RFT’s as a loaner and I could really feel the difference a softer side wall makes. Good luck!

[Posull78]

Thanks everyone for the feedback. I did try the 19s at a dealership today and the ride was better but the car had adaptive as well. 19s in Sport on the adaptive was still a bit better than my current ride (20s on std M Sport suspension)

Considering the following 3 options:
1) Move to 19s. The dealership is willing to swap them out for me from one of their used cars
2) Keep the 20s and move to non run flats … but maybe switching out tires should come after moving down in wheel size?
3) Just sell the car. It has 350 miles on it… MSRP on it is $64K. Maybe I can get $57K? Stings but since I’m not sure #1 and #2 above will be enough to improve the ride, I might be better off taking the loss instead of pouring more money into the car.

What do you all think?

[Isawelvis]

Since you are seriously looking into getting rid of the car. I would do number one, It would not cost you anything and you could still sell the car if you don't like it.

Are the 19 inch the dealer is offering for switch RFT or non RFT If the ride proves better with the 19 inch and they are RFT, you could go to non RFT later.

[MikeG12]

Keep the 20's and get some Michelin A/S4 tires and the improvement will be substantial and you will keep the handling.

[sbt007]

Probably 19 with non-RFT is your best bet. But I am beginning to think that this is not the vehicle for you long term. For me, I have adaptive on 20 inch RFT but I find it to be not that firm even in Sports mode. Handling is a big deal for me. But I don't think that is what you want. You'll have the same "stiffness problem" with performance variants of other makes - like Mercedes GLC43. Or even Tesla. I think Audi SQ5 is the softest.

[zukmeister]

I don’t understand how people buy a performance variant of a vehicle and expect it to ride like a couch. That’s what big American SUV’s are for. They are soft and ride numb. Big boats. Not for me but you may like it.

[XDRESSER]

Much good advice here. For me, it's just interesting to look at the breadth of perspective and taste. I have am '18 M40i with 20" PZero run flats (new to me lease return with 12,500 miles on it). For me, the ride is not harsh but the steering is a little numb, and the turn in is slow, coming off of my long term 2006 E83 (Bilstein HD shocks, 18" wheels, and PZero Zeros non-runflat). I've raised the pressure to 38psi on the fronts, but it has only a small effect in my estimation. Looking forward to a zippier non-run flat tire when I wear through these - hopefully will get the best of both worlds - more responsive with better ride at the same time. It certainly worked that way with my wife's X1 when we moved to Michelin PS4S non run flats.

[Posull78]

Originally Posted by zukmeister

I don’t understand how people buy a performance variant of a vehicle and expect it to ride like a couch. That’s what big American SUV’s are for. They are soft and ride numb. Big boats. Not for me but you may like it.

Not expecting it to ride like a couch, but I was expecting it to run a bit like my 2014 335i on Sport with adaptive. That said, my 335i has 18 inch go flats … and maybe there lies the difference

[335dFan]

Originally Posted by zukmeister

I don’t understand how people buy a performance variant of a vehicle and expect it to ride like a couch. That’s what big American SUV’s are for. They are soft and ride numb. Big boats. Not for me but you may like it.

I actually want and generally get both in this same vehicle. It is cushy enough for me when I want it to be, and it handles quite well in the mountain twisties and freeway cloverleafs, etc. Win-win. If I want it to crash and burn on every road imperfection, then I can always dial in Sport Plus.

[clivem2]

I run 20s with PZero non-RFT on a car with adaptive. The ride quality is very good…but bear in mind that I like a firm, not sloppy ride. Even in Sport the ride is still good when the roads get rough.