I searched in vain for some comments on this matter. Sadly, my run flat Pirellis are pretty much new on the dealer certified 2014 335xi I just bought. My car has the dynamic, adjustable suspension with magnetorheological shocks. I understand the risk of a blowout with no spare tire. Forgetting that, I have two inputs so far: the stiff sidewalls on run flats were accommodated in BMW design. Putting even performance regular ties on the car will ipart a "squishy" feel as the sidewalls are softer, even on Michelin Pilot Super Sports. One enthusiast said he switched back to run flats. The best ties (like the MPSS) are hands down superior and will result in better handling as well as softer ride in all suspension settings. (In this regard, perhaps using MPSS tires and getting Dinan's Shockware software (only $200) would enable the best of all worlds by setting the shocks a bit stiffer in all modes to complement the non run flat tires. Dinan's Scott L says this would improve the car even without his Shockware system. Thanks. Charlie
May depend on how picky you are about the immediacy of turning response/feel. My E92 had 19's on it, with something like 30 or 35 aspect ratio rft's. That wheel/tire combo is so heavy, it made the stock sport shocks feel like they were underdamped, and the response to hitting road bumps just felt like the car was bouncing weirdly. I went to ultra-high-performance regular all-seasons on 17's, with as much sidewall as possible, which vastly improved ride quality, both with the softer, extra sidewall, and the wheel/tire combo being substantially lighter. Since there's no way to rationally or safely explore the car's performance envelope or potential on the street anyway, I'm perfectly happy with the trade-off for everyday driving, particularly considering the generally crappy condition of roads around here. I tote a mini-spare, jack, etc. in the trunk, since it doesn't take up enough space to be a problem for 95% of my usage, just in case of a flat. There is a difference in immediacy of turn in response that is noticeable compared to the ultra-low-profile 19's, but as far as I'm concerned, it's relatively negligible and not significant for normal everyday driving. If you switch out to same-size hi-perf. regular tires, sure, their sidewalls won't be as stiff as rft's, but with the relatively-speaking low-profile aspect ratios, my guess is you'd find as far as ride quality (squishiness), it might be noticeable, but not by much, perhaps almost splitting hairs in that regard - interesting that someone would say they felt there was so much difference they went back to rft's; I would consider their experience relevant as long as their tire choice was comparable to, say, the Michelin PSS's you mention. There's a lot of variation to tires of course, even same-category. Ultra-high-performance tires with low aspect ratios and minimal sidewalls need to have very stiff sidewalls too, although of course not with rft sidewall reinforcement. Still, my experience is only so relevant, the E92 is a different chassis, and mine has sport shocks, and nothing adjustable - apples-to-apples is always the best comparison. If you want to switch your tires out & there's a lot of life on the current ones, the sooner the better then if you were to try to sell them & hope to get at least a little money for 'em; tires only lose value as time passes of course. Yes, perhaps switching tires & running a stiffer shock setting will give a result that works! Oh, to 'watch' a thread, click the "Watch Thread" link top-right above the opening thread comment.
Thanks MGarrison. Two points... 1. I agree the Dinan shockware with MPSS high end tires seems theoretically best approach but my concern here is that the shockware increased stiffness married to the MPSS reduced sidewall stiffness might exacerbate the squishiness of the tire since the loads on the sidewalls would go up with the Dinan settings. I know I am looking at angels on the head of a pin, so for now I think I will see how I feel with everything stock. The car in Sport mode is nicely tossable and I haven't pushed a corner so hard that I feel the tires are limiting my road use enjoyment. I'll see if a local Dinan dealer has some cars I can drive with non run flats to gauge my approach. If the run flats were worn this would be easier! 2. I was looking to receive email notification of replies on my two threads. I do not get them even though I set up a "watch this thread" for the replies. The Porsche Rennlink gives me email notifications when a thread is so chosen...I am sure BMW club does the same but sadly I got no email notifications. If you reply to this with a simple message I will see if it works for this thread. Or I just have to log on daily. Charlie
Hmm, yeah I'd think watching a thread should generate an email - only thing I can think is double-check your profile email to make sure that's correct, &/or double-check your email might not be blocking the alert emails or sticking them in junk mail. I get too many emails as-is, so I just pop-in here quasi-regularly to follow new & ongoing discussions.
I have the same car with the M-sport package and 19 inch wheels. I currently have 18 inch winter rims with non-run flat blizzaks on them. I don't track the car and don't drive really aggressively, but in everyday driving, I don't notice a lot of difference. That being said, yesterday I was going around a 180 offramp and tried 'wiggling' the wheel to move back and forth from inside line to outside line and I did notice some 'squishiness' that I don't remember from the summer tires. The blizzaks are square setup and the summers are staggered. ps - having the extra set of wheels is nice because I keep one of the other wheels in the trunk (yes it takes up room) along with a junkyard $5 jack so I have a real spare.
