So just read a recent article in Car & Driver (this month issue) regarding how larger wheels and low profile tires actually slows the car down, worst for handling, rough ride, and also bad for the suspension.
http://www.caranddriver.com/features...sted-tech_dept

Tell me this isn't true! Was the upgrade to Turbo wheels a waste of $$? Should I downsize to 17 inch boxster wheels on my 997.2?

 

Yep pretty much true. Your 997.2 suspension was tuned for 18" wheels. You can use 19" wheels on the street no problem though but at the track 18's will be better on a Carrera. My 09 Carrera S comes stock with 19" but at the track I use 9x18 and 12x18 wheels.

A lot goes into this and the shocks, springs sways tires and wheels are a package that all work together. Think of the tire sidewall for a minute in taht some side wall flex is good in a turn as it will give and keep more tread on the pavement.

 

My thoughts and always have been....
If you look at their test the difference between the 0-60 times of the 19" versus the 15" is 0.3 second and 1/4 mile times are even closer 0.2 second.......probably in a some what controlled environment/surface.
If you track or race your car then big wheels ARE NOT for you,however,for the street with all variables(dust,dirt,textures etc) the difference is negligible!
The only place you will notice a difference is in ride comfort.
Just need to decide what you want to achieve with your car.....I bought and drive my car on the street with very little spirited drives so I wouldn't trade my 20's for anything and IF I decided to go to the track,I would have a second set of track wheel...

Stacy

PS not sure 17's would even fit over the brakes...?

 

ride comfort is more related to suspension than tire's sidewall thickness. And, after comes the tire's model; some are comfy (and sometimes very spongy/soft) while other gives you EVERY information about the road quality ;-)

FYI:
Sidewall heights

235-40-18 : 3.70"
235-35-19: 3.24"
235-30-20: 2.78"

all approximately the same O.D. (25.5")

 

I just measured my c2s front brakes and few differents 17's wheels we have here and i think the answer is NO.

it takes about 15¼" to completely clear the brakes and I.D. of wheels i measured is between 14½" and 15"

maybe some special wheels model can work though but it's gonna be a very tight fit and i really don't see any benefits doing that.

 

i've tried many set of wheels/tires on my old '78 911 and the 997 and i always ended up with 19's or 20's... But i'm not doing track yet.

The unsprung weight is surely one important aspect to consider but to be honest i don't really feel it on my butt dyno when it's only few pounds of difference on each corner. But i do feel it on braking.

Regarding flex on tire's sidewall, i'm not convinced a 17's or 18's tires set-up would be better because of that. But on 1/4 mile acceleration track i can see the benefit, of course. A tire that cannot flex is not very effective for the launch. But on a track with hard cornering ? I don't know... I would bet the unsprung weight is more involved in the better results.

 

A little side wall flex is also good in cornering...especially if you can stretch the side wall with the widest wheels for the tire.

 

extreme or moderate stretch?

 

moderate....using the tire company info on the widest rim for the given tire size.

 

I really wish I had 18's on my car for comfort & performance, but after seeing how good it looks with the stock 19's I just can't bring myself to downsize

 

I have 18's and 19's, with PASM, and really can't tell any difference in ride quality.

 

The Porsche Marketing Machine agrees with you

 

Not the greatest looking wheels but these are my track wheels 9x18 and 12x18 Forged CCW. You can see the sidewall has a little more beef to it. The tires in thes pics are Toyo R888 245-40-18 front and 305-35-18 rear and are right at the same diameter as the stock 19" with the skinny sidewalls.

 

Do you recall seeing any documentation supporting that?

 

I like my 19s as a mid point. If I tracked my car, I would buy another set of wheels and tires (18s). If I were going to buy new wheels, I would buy 20s (HRE P40) for the street. I think they look great and I couldn't care less if I lose some indistinguishable amount of performance I will never notice. Just my two cents..