I was looking at wheels the other day, & saw they're offering 21's & 22's for the 991....is anyone running these?

 

Ive seen 21's and thought they were too big. Cant envision 22's. Nuts.

 

Car/geometry is designed and optimized to run 19' and 20's. 21's or 22's is OK is you are focused on 'stance'. If you bought the 991 to drive it, stick to 19's and 20's.
Just a personal opinion...

 

Oh, I like stance & all...but was actually looking for a set of 19's so can run some Hoosiers, no 20" sizes.
But almost all the wheel manufactuers are promoting the larger sizes vs. smaller ones.
A 22 with same size diameter would have an inch less sidewall...scary thought there.

 

to run flat out, real 911 guys know they need the biggest they can get.

 

24" and no tires (Real men don't wear rubber). Major savings and boss looks!

 

try your local dealers for some take off 19's from a Base 991.

 

It's annoying enough that 20" wheels are standard on the Carrera S, and offered on the even smaller Boxster/Cayman S. I can't imagine that a 20" wheel was a pure engineering/driving dynamics decision on the part of Porsche. They're simply giving in to popular trends for street looks. If 20" wheels were go-fast parts, they'd be on all the Rolex series (sorry, Tudor) and Continental Challenge cars.

21" and 22" wheels would essentially degrade much of the performance that one pays for in getting a 911--slower acceleration, longer braking distances, worse handling...

I find it ironic that my car will have the 20" OEM wheels as its winter setup with winter tires, while the summer/track setup will be 19" wheels...or perhaps not ironic at all.

 

If you're going to run 22's you really need to go the RWB route.

 

Any chance of explaining why you're unable to imagine the larger wheels are pure cosmetics unbacked by engineering and performance? Porsche has such a long history of designing for looks over performance, for example?

 

I think it is in their blood to have form follow function. I don't understand the physics as well as many of you, but i assume the shorter sidewall on 20" wheels must have some positive impact on lateral stability?

 

and so the dealers can replace suspension components sooner.

 

And charge more for both wheels and tires.

 

Not sure if I'm understanding you correctly, but my point was that I believe that marketing is the main driver behind Porsche's decision to start putting 20" wheels on their sports cars.
To a certain extent. But at some point, the added unsprung weight and rotating mass of larger and larger wheels starts to degrade performance. I will most likely put 255/35-19 and 305/30-19 tires on my 991S for summer and track duty, and despite this being a 19" setup, it will actually have almost the same sidewall height as the stock 20" setup. This is because, overall, the 19" wheel/tire package will have a 0.8" smaller diameter than the stock 20" package. I did this to maintain the same sidewall height, while reducing unsprung weight and rotating mass. The slightly smaller overall diameter will make the speedometer read a bit fast, but I'm willing to accept that.

If, on the other hand, I maintained the same overall diameter as the stock 20" setup, I'd have to go with 255/40-19 and 295/35-19 tires, which would have increased the sidewall height significantly, probably with a resulting decrease in crispness and responsiveness.

My point, then, is that it is possible to go with a smaller diameter wheel and still keep the same sidewall height, as long as you're willing to reduce the overall wheel/tire diameter somewhat. I've heard it said that a wheel's diameter should only be as large as is necessary to clear the brakes--anything else is just excess weight. To a large extent, this is probably true. This is why I think the Boxster S and Cayman S look so silly with their relatively small brake rotors floating inside massive 20" wheels.

 

21s and 22s remind me of what a lot of pro athletes put on their cars. IMO, they look too big and way too showy. Hey, if Porsche puts 19s and 20s on, that's where I'll stay.