[BrettKA7]

When I bought my car, it was a standard 328i with the base suspension and some technology packages. I have made enough cosmetic mods to allow the car to feel more premium, but at it's core, it's still a basic 328i with a base suspension.

I came from a history of FWD Japanese sedans, with the most recent being an Acura TL Type-S with an automatic transmission and whatever the opposite of a limited-slip differential is. It was torque steer galore, and not even Michelin Pilot Super Sports could make it feel safe and sturdy taking a curved road at 70 mph.

The RWD 3-Series is my first German car and was a breath of fresh air, despite it being the worst suspension on the "worst" 3-Series chassis. It felt even better to me when I upgraded to 19" 403M wheels with runflat Bridgestones within 48 hours of taking delivery of the vehicle.

The ride is harsh with that setup; however, I knew the compromise I was making. Dips that don't look too bad nearly shake your fillings loose. I had very even wear, never hit a curb, never hit any dips bad enough to affect alignment. However, 19" wheels with stiff, low profile tires are harsh and loud, and it sounds like the car is being torn apart over a notable road defect.

The base suspension is engineered soft to allow a luxurious ride with hard runflats. However, my 19" wheels with their freshly installed Michelin Pilot Sport 4 S tires are *still* a harder configuration than the original 17" wheels with RFT.

My thinking is maybe the base suspension isn't so bad. It is definitely softer than a Sportline, M Sport, or F8X suspension, but the smaller wheel diameter and hard RFT sidewalls are compromises that seem to be significantly improved by a 2" larger wheel diameter (to bring back some of the stiffness the suspension was designed for) combined with a soft ultra high performance tire that gives a great ride in any situation.

If anyone has thoughts about how right or wrong I am in my findings, I'd love to hear them!j

[Billfitz]

Originally Posted by BrettKA7

Is the base suspension *really* that bad

That depends on your definition of 'bad'. Some think it's too soft, some think it's too firm. In any event, where the stiffness of the ride is concerned a larger wheel with lower profile tire will run harder than a smaller wheel with a larger profile tire, because rubber flexes, aluminum doesn't. RFTs have stiffer sidewalls than non-RFT, that's what allows them to run without air pressure. It also makes them run harder and louder. IMO if you're going to use RFT do so with no larger than an 18" rim, and by the same token if you're going to run larger than an 18" rim don't use RFTs. If you want a softer, quieter ride don't use RFTs, no matter what the wheel size.

[Lancelot]

How old is the car, and what's the mileage? Or did you buy it new?

Harsh is surprising even with 19"/mpss with stock suspension, unless dampers are shot (but i only have experienced msport, adaptive and my current aftermarket coilovers)