I have every intention of adding a 991 C4. Before I make a big mistake and sell my C4S winter package at 25cents to the dollar I was wondering if anyone has any experience on whether they will fit the 991?

Thanks everyone.

 

Ok finally got the answer for this and will share . So yes the fronts will fit fine with a slight difference in offset (marginal) but the backs will need a spacer 15mm or so to fit. So I don't need to sell them

 

Hi Jo!

Listen the circumference on the 997 tires are about 1" smaller than that of the 991.
This means your ABS, speedo etc will be off, if it's more than 4% than the whole ecu will go crazy and give you mayor problems... now if your planing to put them on a C4/S it will damage your awd coupling system as well... not to mention void your warranty!

Then there's the fact that anything smaller than a 19" rim will physically not fit over the suspension components.

Sorry buddy, but the offset is the least of your problems.

Cheers!

 

Bah...that I did not calculate that!

Thanks so much Sid, saved me a bunch of heart ache! Guess I am selling them

 

My pleasure!
Check out Nicoli's ride here in the 991 section he baught some really nice 19" rims, I believe Rottec has them for $1600 bucks and they look really good on the 991.

Cheers!

 

Will do. I got time, most likely going to pick it up next December.

 

Had the same problem, my older snows were on 18" wheels. they just don't fit on the car. I did get a new set of 19" with TPMS sensors mounted and delivered from Tire Rack for less than $2600. The car software is even setup with 4 tire choices in the PCM; 19" summer, 19" winter, 20" summer and 20" winter. It does all the work of figuring out how to deal with the speedometer for you.

 

Ok so help me understand this more. Here are my wheel specs

Dimensions (997 Carrera 4):
Front - Rims: 8.5 x 19 55mm - Tires: 235/35 ZR19
Rear - Rims: 11.5 x 19 50mm - Tires: 305/30 ZR19

Here are the 991 Specs (Base Carrera 4)
Front - Rims: 8.5 x 19 54mm - Tires: 235/40 ZR19
Rear - Rims: 11 x 19 48mm - Tires: 295/35 ZR19

I believe I can I atleast keep the Rims and sell the rubber? The reason I ask is that the RIMS come with separate rubber for summer that I could sell as a packagel. My only question is will the TPMS work?

 

Ya thats cheap, might just do that and sell these. There are too many questions and its not like I have buyer every day of the week for this stuff.

 

hi guys, my rims are 20" Vossen CV3's...don't own any 19's, sorry. Good luck!

 

Oh dude I'm sorry!
My meds are getting the best of me.
On top of it those beautiful 20 concave Vossen rims you've got look nothing like the 19"s from Rottec I was looking at... I must have been doing some wishful thinking!

Again, my apologies!

Cheers!

 

If they're for sale, I'm interested in buying your wheels (and tires). I want a dedicated winter wheel & tire set for my 2010 997.2 Targa 4S. I've been targeting 18" wheels because of he larger selection of winter tires, but will also now consider 19's. :-)

 

Would be interested in the price. Prefer these wheels to the ones I have...going to have on mine.

 

That's the first I've heard of this on any 911 generation... man that would really suck!
I have my all cars tires changed at a specialty shop, if changing to winter tires (and back) on the 991 has to be done in conjunction with the proper setting in the ecu than that would be a problem...

I'm going to ask my mech. at the dealer about this but would appreciate if you could expand on your post.
To this end here's some questions you could help me with.

1. Do you know why this has to be done... the overall diameter of the wheel + tire is within 4% (ie. the rotations per mile) for all the options mentioned above (19" wheel is smaller but has larger/higher side wall tire).

2. Does it (ECU setting) only regulate the difference in circumference (if I'm wrong and it is greater than 4%) or does it also change the throttle mapping, shift points etc specific to winter/slippery conditions?

3. Is this something which has to be done through the ecu or can this be accessed through the cars instruments (stalk etc.)

4. How did you find out about this?

Sorry for all the questions and thanks for the heads-up!
Cheers!

 

Sid,

I hazard a guess it has to do with tire pressure for the different sizes and seasons. I think it occurs when you change over tires, the system detects the new TPMS and asks for the new config.