[simoneves]

I've had my 2016 228i with THP and PSS tires for 2 weeks, and while I love it to bits in general, the steering feel (coming from an E93, and an E82 before that) really is rather disappointing. I knew it wasn't going to be great going in, so I'm not really complaining, but... OK, I'm complaining a little...

I have carefully set the tire pressures (33F 38R) but it still feels pretty wander-y at speed, even in Sport mode. I find myself having to make small corrections more consciously than I'm used to, perhaps simply because I can't do it SUB-consciously any more because of the relative lack of feel.

While it doesn't really feel that different from the three M235is I drove while testing, I am wondering if it's up to spec.

It just went back to the dealer to get some paint chips fixed and the satellite radio enabled (long story, see other thread) and they gave me an 2015 F34 328i X-drive as a loaner, and frankly I almost prefer the steering in that. It's (even) lighter (and doesn't seem to get heavier in Sport mode) but it has stronger self-centering, and doesn't feel like it's wandering so much.

I think I'm going to get the alignment on mine checked, as honestly I don't trust the dealer to PDI their way out of a paper bag.

Has anyone else found a sensitivity to alignment and/or pressures?

[Tpeterson]

I put 35 PSI F/R in the tires and the car drives much better. It eliminates some of the of the understeer. Get a Dinan Shocktune and it will eliminate some more of it. My 228i doesn't wander at highway speeds and beyond.

[dah]

Mine seems OK, vague but not wandering. I have wondered why a 50/50 balanced car needs higher pressure in back. All other 'performance' cars we've had were the same all around - Prelude, SLK, S2000, Focus ST, TL. My 335i had more pressure in back just like the 2.

[Sportstick]

Originally Posted by dah

Mine seems OK, vague but not wandering. I have wondered why a 50/50 balanced car needs higher pressure in back. All other 'performance' cars we've had were the same all around - Prelude, SLK, S2000, Focus ST, TL. My 335i had more pressure in back just like the 2.

Anticipating the cargo capacity of the trunk.

[simoneves]

I'll experiment some more with the pressures. Any feel for how accurate the on-board measurement is? I've never had a car which tells me the actual pressures before, only the simpler systems which detect a low tire from the change in wheel speed.

As for why it's higher in the back, again I always assumed it was because of the wider tire needing more pressure to keep it "flat to the road" (my E93 M Sport with the same size tires both ends was 35/42, probably because of its fat arse!)

[Tpeterson]

Originally Posted by simoneves

I'll experiment some more with the pressures. Any feel for how accurate the on-board measurement is? I've never had a car which tells me the actual pressures before, only the simpler systems which detect a low tire from the change in wheel speed.

As for why it's higher in the back, again I always assumed it was because of the wider tire needing more pressure to keep it "flat to the road" (my E93 M Sport with the same size tires both ends was 35/42, probably because of its fat arse!)

My on-board measurements are 2 psi lower than the two gauges I've compared it to,one digital and one analog.
More pressure in the rear than the front tires means more understeer. BMW probably does this for safety and liability reasons. Lawyers overruling engineers.

[simoneves]

Originally Posted by Tpeterson

More pressure in the rear than the front tires means more understeer.

How come?

[Tpeterson]

Originally Posted by simoneves

How come?

On street tires more pressure more grip;less pressure less grip.Street cars are engineered with understeer,so putting more grip in the front and less in the rear moves the handling towards neutral. I'm not an engineer,but that's my understanding on how it works. The link below at least backs up my previous post.



http://store.uucmotorwerks.com/artic...ybar_setup.htm

[RWDdrifter]

Originally Posted by Tpeterson

On street tires more pressure more grip;less pressure less grip.Street cars are engineered with understeer,so putting more grip in the front and less in the rear moves the handling towards neutral. I'm not an engineer,but that's my understanding on how it works. The link below at least backs up my previous post.



http://store.uucmotorwerks.com/artic...ybar_setup.htm

Thanks for posting the table. It makes sense. I'm thinking of getting four 18x8 wheels in the Spring along with MPSS tires (keeping the 461M staggered wheels and AS3 tires for the winters). With the squared wheel config and all tires at 35psi the handling should be fairly neutral.

Also, I expect that at 35psi rather than 32psi the front wheels would be a little less prone to pot hole damage. Big pot holes will still damage the wheels, but every little bit of margin helps.

[nike001]

Originally Posted by Tpeterson

On street tires more pressure more grip;less pressure less grip.Street cars are engineered with understeer,so putting more grip in the front and less in the rear moves the handling towards neutral. I'm not an engineer,but that's my understanding on how it works. The link below at least backs up my previous post.

Yes, this. Nothing to do with trunk loads.

More pressure in the rear/less in the front helps eliminate oversteer. I use 36front/38rear and am quite happy.

[Tpeterson]

Originally Posted by RWDdrifter

Thanks for posting the table. It makes sense. I'm thinking of getting four 18x8 wheels in the Spring along with MPSS tires (keeping the 461M staggered wheels and AS3 tires for the winters). With the squared wheel config and all tires at 35psi the handling should be fairly neutral.

Also, I expect that at 35psi rather than 32psi the front wheels would be a little less prone to pot hole damage. Big pot holes will still damage the wheels, but every little bit of margin helps.

I wish BMW would quit with the staggered fitment. The cars would handle better.
If the wheels are wide enough,you could go with 255/35 tires because ,if you do the math,they are the same diameter as the stock 225/40 fronts unlike the stock 245/35 rears which are slightly shorter.
I'm on my second set of PSS on a BMW.They are the best performance tires I've ever owned.They're quiet through the full tread wear,they stick like glue,and they wear reasonably well.

[OpenAir]

Originally Posted by nike001

Yes, this. Nothing to do with trunk loads.

More pressure in the rear/less in the front helps eliminate oversteer. I use 36front/38rear and am quite happy.

+1

I'm at 34 front / 36 rear.

[2Banger]

Originally Posted by nike001

Yes, this. Nothing to do with trunk loads.

More pressure in the rear/less in the front helps eliminate oversteer. I use 36front/38rear and am quite happy.

I will try this, Sounds good!

[CE750Jockey]

Ok, I must be doing something wrong. I just swapped my Michelin PSSs for the winter tires, 215/50R/17s and put 33F/41R, per the tag on the door and the Owner's manual. How come nobody else here has listed the same pressures? Isn't that what what they're supposed to be at?

[Sportstick]

Originally Posted by CE750Jockey

Ok, I must be doing something wrong. I just swapped my Michelin PSSs for the winter tires, 215/50R/17s and put 33F/41R, per the tag on the door and the Owner's manual. How come nobody else here has listed the same pressures? Isn't that what what they're supposed to be at?

The door label is for maximum vehicle gross weight...full passengers and cargo. You can comfortably carry yourself, and a significant other (on two feet or four) at lower pressures. I'm running 36 front and rear on 225/45-17 Pilot Sport AS3 which feels good for steering and doesn't make the back end overly bouncy as well as gives me some leeway for temperature fluctuations, as I realistically don't check tire pressures with each daily change in the weather.

[CE750Jockey]

Originally Posted by Sportstick

The door label is for maximum vehicle gross weight...full passengers and cargo. You can comfortably carry yourself, and a significant other (on two feet or four) at lower pressures. I'm running 36 front and rear on 225/45-17 Pilot Sport AS3 which feels good for steering and doesn't make the back end overly bouncy as well as gives me some leeway for temperature fluctuations, as I realistically don't check tire pressures with each daily change in the weather.

Gotcha! Thanks, 'Stick! I'll adjust when I get home.

[Viffermike]

Originally Posted by Sportstick

The door label is for maximum vehicle gross weight...full passengers and cargo. You can comfortably carry yourself, and a significant other (on two feet or four) at lower pressures. I'm running 36 front and rear on 225/45-17 Pilot Sport AS3 which feels good for steering and doesn't make the back end overly bouncy as well as gives me some leeway for temperature fluctuations, as I realistically don't check tire pressures with each daily change in the weather.

This, as well as the built-in understeer mention. Of those other performance cars mentioned by dah, only two of them are RWD (S2000, SLK), and neither of them make enough power or torque low down in the rev range to get into serious trouble with. The 2-series does. It's liability control for those many BMW buyers who don't buy the car for performance; they buy it for status.

I've found my RFT sweet spot at 35F/36R. I'll have to do it again when I switch to regular tires.

[dah]

Fwiw, my Focus ST required 36 psi all around on supersport tires. I had a loaner Focus Titanium with the same tire sizes, 39 psi. Hmm. So it is certainly not based solely on weight and power. Probably fuel economy trumps all.

[AlpsRider]

Originally Posted by dah

Fwiw, my Focus ST required 36 psi all around on supersport tires. I had a loaner Focus Titanium with the same tire sizes, 39 psi. Hmm. So it is certainly not based solely on weight and power. Probably fuel economy trumps all.

Isn't the Focus FWD? Anyway...fuel economy, safety and ride comfort are all factors that I'm sure they consider when recommending tire pressure. Performance is probably a lower priority.

Michelin UK website PSS inflation pressure recommendations BMW M235i staggered.
FRONT 31.91 loaded: (36.26)PSI
REAR 31.91 loaded: (43.51)PSI

To me 31.91 psi is marshmallow soft. I can't imagine why the Euro spec is so low.

Tested with me (175 lbs.) in an empty M235i staggered MPSS.

Previously I tried 36 psi front and back, 36 (35.1 on the car computer) was too soft for me on the rear tires, they were rolling over a bit in extreme cornering situations. I felt the mushy roll over in slaloms and also saw it on the tread, I even had a little fish tail with high power cornering acceleration in Sport+.

I have inflated my staggered setup (58 degrees cold inflation pressure with no sun in the garage) to 36 front and 37.5 rear with my digital guage, the car computer registers 35.1 front and 36.5 rear. I'm still experimenting, but so far I like the way it feels, crisp with minimal jittery bouncing. When the ambient temperature outside was 80 degrees, hard driving on the twisties pumped them up to 42 front and 43 rear. Sliding was controlled and predictable (no fish tailing). It definitely makes me appreciate comfort mode on the concrete freeway though.


Does anyone else have the drivers side front tire (M235i) heating up more than the others? I wonder if it is a faulty sensor or engine compartment heat. I have recalibrated several times, it's not that. When I drive the car the first time for the day, they are all even temperature.

[BarryJI]

Originally Posted by AlpsRider

Does anyone else have the drivers side front tire (M235i) heating up more than the others? I wonder if it is a faulty sensor or engine compartment heat. I have recalibrated several times, it's not that. When I drive the car the first time for the day, they are all even temperature.

I have this issue, or something similar, in my 228i M Sport with THP and Michelin PSS tires. The driver's side front sensor seems to be consistently ~.5 psi off. Much as I like the iDrive electronic pressure sensor display, I trust my digital tire gauge first and foremost.

FWIW, I run 34/40 and with the Dinan Shockware suspension tune there is no excess bounce or roll. The car handles very well but I am pretty sure it would understeer at very high cornering speeds and the steering, while efficient, feels a bit "detached" from the road, a drive-by-wire characteristic, I suspect.

[AlpsRider]

Your 228 may be lighter in the front end than my 235 so 34 is probably ok for you. I agree that I trust my digital tire guage more than the car. It is interesting to see the change in pressure and temperature depending on driving style though. In town, my front tires heat up from the engine I suppose, which leads to higher pressure in the front. I need at least 1.5 psi more in the back to keep the fronts from having more pressure than the backs in town. On the highway the back tires heat up.