Techs at dealers say to stay with 19" because Porsche designed car around them....and a couple rim dealers said the same. These 19" still riding rough even with lower 33/39 pressures. Liked the 18s on my M3 over the 19s, but still would like to hear if anyone with these tts are using 18s??

 

I would imagine that your car would drive better with 18s .. provided they can fit over the brakes.

 

18" wheels would fit fine over the steel rotors but not the ceramics.

 

Two porsche dealers and a couple of wheel sellers have all said leave the 19", 911 tt is designed around the 19", so stay with it. But I understand 18" are used on the track. What bothers me, will any of the electronics be messed up with 18" like PASM and PSM. When I asked Porsche (the 800 #), they said check with dealers on this subject. I know with my M3, by leaving 18", but going to P2 with slightly different sizes, the low tire light would come on every time I would put the factory tires/rims back on the car. I was just wondering if anyone out there actually was using 18"on the street on their tt??

 

I think the dealers/shops are pulling your leg..

1.The 18's run 235/40-18 and 265/40-18 (From the Carrera / Carrera4)
The 19's run 235/35-19 and 305/30-19 (From the Carrera4s / Turbo)

Thats a 0.3% difference in the front wheels and a 0.5% difference with the rear wheels. I don't think thats a big enough difference to justify a problem with the turbo running 18's.

2. If the cars were designed for 19" (and nothing else); then you wouldn't find people running 20" rims on the car.

3. Porsche sells a 18" winter wheel for the C4S (which runs 19" at the same offset/size as the Turbo).

4. The Low-Tire light would show up from the amount of PSI you have in your tires .. as long as your running within spec, it shouldn't give you any problems.


FWIW, If you don't have the ceramic brakes .. I would go for the 18"s (if drive-ability is your main concern).

 

Porsche shows a winter tire 18" for the rear at 295/35(18) which makes it even closer to the 19" ( 305/30) than the ones you describe above @ 265/40(18). I think you are right, as long as the diameter of the wheel is very close to the factory one, all electronics will stay within specs.

I know with my M3, when I went from factory 18s Ft 245/40, rears 255/40 to BBS (RGR) ft 245/40/18, rears 275/35/18, the tire low pressure dash light would stay on. But on BMW, I am sure the light was covered by rotation distance, not pressure like Porsche. Thanks for the info, want to get another set of better looking rims, but with that, I want them much lighter in weight and why not get more riding comfort too.

 

I use 18" Carrera III's as my track wheels with 245/35/18 front and 305/30/18 rear tires. No electronics probs and I drove the car from the track into town for gas and food. Very comfortable on the street even in R-compounds

 

I havnt seen a racecar with 19s...18 is DEFINITELY the prime rim to run for performance and SOME try to even run 17s (like on Turners M3)...

I just dont see why the car would be built for 19 when its a. not the best size for performance and b. when they KNOW drivers will want better performing wheels/tires...

 

Porsche wouldn't answer the question on 18 v19 when I called. They said go with whatever dealer says. I think too, that 19" is there just for looks. On the track 19" can come apart is the reason for at least 18". I am going for much lighter rims than come with my tt, and will go for 18's as well.

 

ya, I and MANY others agree that the 18s offer the best EVERYTHING (durability, weight, looks, price...etc) and are simply the best bet for any REAL performance application.


HOWEVER...the 19s look damn sexy...