19" wheels on 2001 C4 (3.4L)?

G'day, I've got the stock standard 17" wheels on my 2001 C4 (3.4L). Rear left tire's getting a a little worn; what an opportunity to change the whole set :-). But I don't know about this kinda stuff, so :- 1) Can I go to 19" safely without having to change suspension, springs, etc.? 2) Being a constant all-wheel drive, do I have to be concerned about front/rear circumference being in sync? (yes I'm using the completely wrong lingo here, but hope you understand what I mean) Apologies if I'm asking really stupid questions here. Cheers, Sean

I would "upgrade" to 18" wheels and tires, you can go with 8" fronts and 10" rears and use 235 and 285 mm wide tires respectively. Anything larger either in diameter or width may cause problems and ultimately decrease performance. As tire and wheel sizes grow, the chassis must become more rigid and the suspension components need to handle increased loads. The 996 was designed for maximum performance using 18" wheels or less. 19s on a 996 make a statement that the bling factor trumphs performance. Save it for the Escalades.

Go with what you want....19's are not an issue with the 996...I experienced a performance upgrade as well as I guess "bling factor"....i also have PSS9's and the car is lower than stock....

In a Porsche 911 Buyers Guide that I purchased some time ago, they strongly urged the use of 17 or 18 inch wheels on the later 996 models as the use of 19s caused vibrations that could crack the windshield and cause suspension issues. I can't remember if anything was specific to AWD or not. If I can find the book I'll post it and might be able to pull something from their site.

I both agree and disagree with Nick. I think you could find lightweight 19" heels and tires that will work with your C4. You are correct in your understanding that you need to minimize the variation in tire diameter from stock so that it will not damage your AWD system (I don't think you really want more than a couple of percentage points of variance). However if the variance is in the same direction (i.e. both the front and rear are 5% larger) I think that will be just fine as the variance front to rear will stay the same. However, Nick is correct that the 18's are really the "performance" choice and the 19's a bit of the "bling" choice. The shorter sidewalls on the 19's will degrade your ride and force your suspension to work harder to maintain good contact over broken pavement (the 19's will be a little heavier than a similar stlye in 18's). I believe the differences will be "slight", but they will be present.

Again....different wheel/tire/suspension combos will give you different results...BUT....my wife HATED driving the car on 18's....Stock twists....When I put the 19's on the car she raved about how much "smoother and less bumpy" (her technical terms...lol) the car was....She thought I had to have changed the suspension? I am running relatively soft settings on my PSS9's, but maybe the wheel/tire combo just works better with the PSS9's....who knows but to make a blanet statement about it is false...Also my handling is better as I have wider wheels and tires...more contact patch...yes I cam get the same widths in 18's, but if comparing these to stock...the 19's perform better.

The "stock twist" is the heaviest wheel that Porsche offered for the 996. I'm mot sure which "twist" you had but the Turbo Look I's weigh over 30 lbs in 10" rears and the Turbo Look II's are over 26 lbs in 18" x 10" (remember the Turbo got the much lighter hollow versions of this wheel. Other Porsches got the heavy/cheap solid versions). It is possible that your 19's are lighter than that wheel and may actually ride better in spite of the profile decrease (tires could also play a factor if you switched brands). However, your 19's will ride more firmly that the same wheel in 18's for two reasons. First , you need lower profile tires to fit (or else you will dramatically alter the gearing). Second, they will be heavier. I assume you are running on 19 x 11's? You could run in 18 x 11's and have the same contact patch but run a taller profile and have a lighter wheel right? I'm not suggesting you should as the wheels look great on your car and you obviously like them. I'll be the first to admit that the 19's look very cool on a 996 (I struggled with the decision when I moved to my new wheels, 18 x 11's). However, whenever I found a wheel I liked and I looked at the weights the 18's were always lighter than the same version in 19. So it comes down to a compromise......the 19's sacrifice a little ride and handling for looks and the 18's sacrifice a little bit of the look for ride/handling. I would not say either choice is wrong, but the compromise (small as it is) does exist.

Here's 19s on mine. Ride is a little firm but OK. I have a lowered sport suspension, no rubbing isssues with 275/30 on rear. The 285s did rub a bit, probably would not have with stock suspension.

You can run up to 295's even on a lowered car. What are your offsets? 285's will not rub unless the offsets are wrong...

The wheels were on the car when I bought it, and there are spacers on the back, that probably is the issue, pushes them out just enough so the 285s rub when you hit a bump.

Ray you are completely correct except my wheels are not available in 18"...They are 19" 997 Sport Designs which are probably lighter than my 18s by alot. You are also correct that with the correct offsets you can run a 295.....I have 19x11 rims with 295/30/19 my offsets are 67 in the rear.....it has about 1/4" room as well....

That's what I used to think as well, but it's not as cut and dried as wider tires=bigger contact patch. Here's an insightful post from the Racing and Driver's Ed Forum: "Here are a few note about choosing tires. If you want to learn more, I would suggest tasking the Evolution Driving School Dial-in Course (run by multiple SCCA national champs). 1. If the weight of th car has not changed are you are running the same tire pressure with 2 differnt width tires, which has the larger contact patch? Neither, they are the same. Only the shape of the contact patch changes. With the narrower tire, the contact patch is more narrow; but longer. The wider tire has a wider, but shorter contact patch. 2. How do you increase contact patch for more grip? The only way to increase contact patch is to run a lower tire pressure. 3. The larger the tire, the wider the section width. How could this be an issue? A larger section width can significantly effect turn-in. A stiffer sidewall, will have less flex and react quicker. A wider sidewall will always have slower turn-in. This is because when you turn the wheel, the wheels first change their angle of attack. The car continues to want to go straight until that angle of attack has changed at the tread. Since the tread has friction with the surface, it resists movement. The sidewall flexes until it becomes full stiff and the transiant loads allow the car to turn. So now think about putting a wider tire on the same wheel, you have to decrease tire pressure to get more contact patch. This makes turn-in far worse than the original tire setup. 4. So what does all this mean? It means run the rigth tire for your car a fluxuate tire pressures for optimum grip. If you want more grip, you not only need a wider tire; you need a wider wheel to run it on. This reduces sidewall flex and allows lower pressures to be run." - 02 Carrera

thats saying what I said...I went from a 10" rim in the rear to an 11" rim...I went from a 285 tire on a 10" to a 295 on an 11"....So I now see why my car reacts quicker.....My fronts are still 8" rims, with now a lower sidewall...faster turn ins....all according to your quote.....I can say this is exactly what my car feels like...much quicker reaction than it used to have.....Its a C4 so it had lot of understeer....the PSS9's took care of most of it, the 19's did the rest. I am using the 997 sizes, and I am sure Porsche went with those for a reason on the 997.

As usual, those who "have" believe and those who "don't", don't.

I'd say most of what '02 Carrera had to say is relatively intuitive, like the shorter sidewall with a wider wheel being more reactive steering-wise, but the fact that the contact patch doesn't increase on a wider tire unless you lower the tire pressure was honestly something that I'd never thought about.

G'day folks, Bit the bullet and went "bling" (i.e. 19"). ST-Meister SP3-RS 8.5J-19 fronts and 10J-19 rears. Tyres are Pirelli P Zero Rosso 235/35ZR19N1 fronts and 285/30ZR19XL rears. I asked about going to 295/30's but difference was too great. Also note that the rears aren't N1 rated but the chap said it was ok. Don't know if he was BS-ing me or not. Link to photos from my home page :- http://www.anakchan.com/gallery/NewW...2_enterAlbum=1 I'm probably subconciously kidding myself here but these new wheels/tyres ride smoother than my old ones! Few things to note about my old tyres though...rear left quite worn in comparison to the others (balancing issue?) and right rear are different brand from the other 3 as original got nailed and closest garage didn't have Pirelli's (so went Goodyear). Sean

Sean - your new wheels look good! In general, design wise, they remind me of GT3 wheels.

The 19 isssue with degraded performance is a bunch of BS. Most people will never drive the car at the level that they can feel the difference in performance. With that said I have 19 with 235 and 315 on a C2 2001with row m030. From my experience I can tell you 19 look great, but there will be no improved performance. The ride does degrade a bit, but not that much. Its up to you as with your style and wants. The best advice is to ride in some cars to see if you like the ride.

I have 19s on mine, cornering is better over the 18s and the drive is just a little bit more bumpier but otherwise, I wont be turning back to 18s

My '04 with 19" Champion RG5s (which are lighter than any factory 18s) handles like a champ, and the car has been lowered with H&R springs. Although the 996 was supposedly optimized for 18s, 19s can be made to work quite well (mine was set up cy Champion Motorsports).