StumpJumper

that is just patently false

do they look better? maybe but that is subjective

do they perform better? I'd bet they are worse in nearly every measurable performance area except maybe skid-pad where the larger contact patch & stiffer sidewall should help

unsprung weight is bad, unsprung rotational weight is even worse

troposphere

Handling and road/steering feel may be subjective, but I notice a difference.

Can it be measured? Who cares, it just makes driving more fun.

Any difference in unsprung weight is not noticeable, at least to me.

Tweakophyte

I remember an early review stating the 18s were perfect and the 19s were a little harsh. (inside line?)

The 18s seem more practical, and in a snowy area you could have one set of rims and rotate tires instead of having a summer/winter set of rims.

westwest888

The 19" look great and if you're coming from BMW don't worry they are 1" bigger in tire diameter. Don't worry about the weight - the brake rotors are made of iron the the calipers steel. Components other than wheels+tires make up 60% of the unsprung weight.

sakimano

Don't worry about weight? He wants performance.

Comparing the chassis or unsprung weight to the rotating mass in the wheels/tires is absurd. They're not even remotely similar, as far as an effect on the car goes. Changing to light weight rotors will have another big effect on this car. Changing brake calipers - almost none. Anyway, if the attitude is 'don't bother because you can only change a small portion of the unsprung weight'...why would anyone ever mod the car? Don't bother with a tune...you're only going to gain 7%. Don't bother with a de-cat. You're only going to gain 3.5%. All these little changes add up to a very serious impact on the car. Some would say a complete transformation. Same is true for rotating weight. When you guys have JHM LW flywheel + LW rotors + LWtires/wheels on a B8, to go along with the obvious power mods like tune + full exhaust, you'll see another level of awesome performance from these cars.

Stock wheels are around 30lbs + 27 lb Dunlops in many casse. That's 57 lbs per corner. Getting into some 21 lb wheels and 24 lb Michelin Pilot Super Sports will cut 48 lbs rotating mass off the car...and it's rotating quite a ways away from the hub. It will feel like shedding over a couple hundred pounds.

p.s. the two fastest B8 S4s in the world are primetime and 81bear...and both achieved their fast times with lw wheels to compliment their other mods. A boatload of other guys can't get close to them. Why? because they say 'don't bother' to the little things.