I am in the process of ordering a new basic 991.2 and am conflicted of wheel selection. The basic car has 19" wheels but I don't like the wheel design. I much prefer to order the 20" classic Carrera wheels. I have 2 questions.
1. Will the ride deteriorate with the smaller side walls of the 20" with the PASM package?
2. since I live in Florida with frequent rain and thunderstorms will the wider tires be more prone to hydroplaning?

 

1. Probably, but only slightly.
2. Tire size is independent of hydroplaning as the contact patch is the same size (area). The tread design, siping and depth is what determines resistance to hydroplaning.

 

I thought I wouldn't like the 19" wheel design all that much either when I ordered it (as I wanted 19", even though it might only make a small difference, I still wanted it). At the time I just thought that if I really didn't like it I would find a pair of nice aftermarket wheels but now that I have the car, I actually REALLY like the design.

For your questions: I don't think it makes a difference for rain (it'll suck either way), and the comfort isn't really that much different either. I wanted every bit I could get as I use the car as my dally driver, but it might be more price efficient to get the 20" with the car and if you really want some more comfort, get 19" aftermarket.

I would love these:

http://www.fuchsfelgeusa.com/wheel/1...e%2Dfuchs%2D19

on a metallic green (racing green metallic) car, but I got GT Silver and the 19" wheels. Happy with my decision.

 

we've had a lot of rain in Toronto this year including some intense downpours - I was initially worried but have not had any issues with the 20" on my 991.2 C2S - I find the grip amazing dry or wet

 

1. I upgraded to 21" aftermarket and and am very impressed with the ride quality.

2. I live in FL as well. We had a very heavy storm on Sat with water accumulating on the interstate. I have Pirelli P Zero tires (with 325's on the rears) and expected to potentially have issues. I had none, car performed great. I was not driving inappropriately, which is important, but I was going with the flow of traffic so at a decent rate of speed.

 

I don't know how the 19-inch tires compare with the 20s in their resistance to hydroplaning, but wider tires do not help. Even if the contact patch has the same overall area, a wider tire has a harder time shifting water away from the contact patch.

In the extreme case, this is the reason why motorcycles don't hydroplane.

 

The widths are the functionally the same (10mm difference) so it does not matter much for rain. You do give up some ride quality going to 20s but again, we are talking low profile tires in any case. Why there are not 18s or even 17s I am not sure. I suppose the pizza size brake discs won't permit them.

I ordered 19s because I think they look good and narrrow by 10mm is fine with me.

 

1. YES
2. YES

I have 20" on my 991.2 C4S because that's what it comes with.
I have 19" Winter wheels for it.
I also have 18" on my Boxster.
If not for the widebody and HP on the C4S, I would have 19" all the time.
20" are noisy also.-Richard