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[Cardis]

hey folks, bought my 2012 128i with the m package in Lemans Blue back in 2013..been l0ving it since..I have 65k Km on it..it is my baby. Last year I needed to change the tires..and couldnt get the run flats anymore in that size..I got good replacements..cant rememebr off hand..and I ll check, but ever since I changed them, the car doesnt seem as glued to the road..im wondering if it because the suspension is set for the harder side wall of the run flats..it's not the same car..still drives great but it use to feel liek I was on rails..should I increase the PSI?

[mkeiser]

there's lots of variables to this. what size and kind of tires are on the car now? what psi are you running? the 'on-rails' feel is very subjective without any quantitative data to back it up. You could probably chalk it up to changing from a tire with very stiff sidewalls (run flats) to a tire with relatively soft sidewalls (whatever you have on now). PSI could be a bit of a factor.

[BMWCCA1]

If you can't remember what tires you bought, then neither can we!
You have to be in touch enough with your car to feel the handling difference but to put up with it for a year and not know what tires you have could mean you got sold some gas-station brand and maybe even the wrong size or aspect ratio. Go check your tires and come back to us with the brand and size you have on there now. I'd hazard a guess that there are more of us here without runflats these days than still have them, so we can probably help—given some more information!

[Cardis]

love it..if you can't remember neither can we! lol..I got the staggered Firehawk Indy 500 the rears are 225/45R17 94W and the front are 205/50R17 93W..im running at what it says on the door, I think it is 35psi in the back and 33 in the front..the car just doesnt feel the same..when getting on the highway for instance or driving at higher speed it just doesnt seems as stable..I use to be able to point and go and now the car when driving straight is fine but changing lanes the cars seems to waiver a bit..car is bang on straight if I release the wheel..that's why I thought I should maybe raise the PSI to stiffin up the sidewalls a bit

[Cardis]

Originally Posted by BMWCCA1

If you can't remember what tires you bought, then neither can we!
You have to be in touch enough with your car to feel the handling difference but to put up with it for a year and not know what tires you have could mean you got sold some gas-station brand and maybe even the wrong size or aspect ratio. Go check your tires and come back to us with the brand and size you have on there now. I'd hazard a guess that there are more of us here without runflats these days than still have them, so we can probably help—given some more information!

very funny..I even took pictures now!

[cerealwars]

Firehawk Indies are solid tires for the money. They should grip WAY better than the runflats. That pressure sounds high to me, personally. I run 28-30 in the front and 30 in the rear. Lower pressures should make the car grip better.

Also consider rear subframe bushing inserts to firm up the handling in the rear.

[Suprgnat]

Originally Posted by cerealwars

Also consider rear subframe bushing inserts to firm up the handling in the rear.

At the least. Full bushing replacement with ///M or solid even better.

[WeryPert1]

+1 for replacing the Rear Sub Frame Bushings to correct this. Or at least trying the inserts.

The consensus seems to be that when these cars first came out, the 1st-gen run-flat tires were quite stiff, and to compensate BMW chose a softer RSFB material. So with better, softer tires nowadays (especially non-runflat) the whole rear end is too squishy/soft. Mine certainly was awful, and new RSFB's 100% cured that. I went with the 2-piece Whiteline poly's.

[Cardis]

Originally Posted by Suprgnat

At the least. Full bushing replacement with ///M or solid even better.

Ive gone through your build a few times..it is so impressive..I see this listed under bushings on your list • BMW M3 Rear Sub-frame Bushings

Do you have the part # for what you recommended? Appreciate it, thanks

[Suprgnat]

Originally Posted by Cardis

Ive gone through your build a few times..it is so impressive..I see this listed under bushings on your list • BMW M3 Rear Sub-frame Bushings

Do you have the part # for what you recommended? Appreciate it, thanks

2X 33312283382 RUBBER MOUNTING front
2X 33312283383 RUBBER MOUNTING rear

I'm currently finishing up a new ///M rear suspension carrier with solid aluminum bushing. I bought the ///M specific aluminum bushings from Millway. Lots of reputable companies make them.

[Cardis]

thanks! Wow you are having tons of fun with mods for sure!