17z for b6 S4

[B5man17]

I know the 18z are a popular upgrade but I don't want to go to 18in wheels. The rotors with the 17z would be smaller then stock but I would think you would still get the performance benefits of having better calipers.
What is everyone's thoughts on this?

[moyenecorniche]

Not sure where your thoughts on this are but ...
18's are oem for the S4, reducing the wheel diameter and increasing the tires profile will decrease handling response. As for the brakes.... Why ??? If you put 17" rotors which I think are 280 mm that is a smaller circumference which will (1) increase heat retention and (2) may not even function properly.

Can it be done ? Yes, but it is not optimal... The engineers designed a brake system for the S4, rotors and calipers are sized to work efficiently. You can and should go up to a larger diameter but decreasing rotor size is the wrong approach..
Personally on a 3900 lb V8 powered quattro performance sedan I would want to assure that I have the best braking performance possible...
Why most of us go from the single piston caliper to a 4 or 6 pot caliper and increase the rotor diameter....

One thing I hated on the B6 A4 was the 17" wheel and undersized rotor / caliper. Installing the S4 caliper without increasing rotor diameter would not have been an upgrade.

[LINDW4LL]

I hate the principle of decreasing your rotor size as compared to stock.

[moyenecorniche]

With an S4 or an RS4 Form always follows function.... Not trends based on static popular mods. A performance car capable of 160+mph needs to be able to stop quickly..

[B6_4.2]

Would it stop the car? Yes
Would braking be improved? Not for long... Since the majority of your heat dissipation is coming from your rotor.

So unless your only concern is reducing unsprung weight, so you can go fast in a straight line a few times, I'd go up in size if changing anything.

[BCsniper]

18's are oem for the S4, reducing the wheel diameter and increasing the tires profile will decrease handling response.

How so?

If you are able to get a bigger tire on a 17" wheel, why are you losing handling response. You can get a tire with the same width, even more meat on it, with a wheel that's more lighweight. That sounds MUCH better to me than so many people here that like to run heavy 19" wheels with stretched or skinny-ass tires

[noob5]

How so?

If you are able to get a bigger tire on a 17" wheel, why are you losing handling response. You can get a tire with the same width, even more meat on it, with a wheel that's more lighweight. That sounds MUCH better to me than so many people here that like to run heavy 19" wheels with stretched or skinny-ass tires

I think Moyenecorniche is referring to the issue when dealing with larger sidewall. Typically, the larger sidewall will have more "give" when changing the direction of travel, leading to the feeling of the tire being less responsive.

[moyenecorniche]

How so?

If you are able to get a bigger tire on a 17" wheel, why are you losing handling response. You can get a tire with the same width, even more meat on it, with a wheel that's more lighweight. That sounds MUCH better to me than so many people here that like to run heavy 19" wheels with stretched or skinny-ass tires

As Noob5 points out I was referring to increasing the sidewall, going on the assumption derived from OP's info.. In other words reversing the +1 factor of a larger diameter wheel fitted with a smaller profiled tire. Going from an 18" with a 235-245 / 40 to a 17" fitted with a 235-225 / 45-50 will affect handling in a loss of response and probably other factors.
The S4 is a lot heavier up front than an A4. It tends to understeer and increasing tire profile while at the same time reducing width will result in increasing understeer.

As for 19's, I am not a fan of them for the B6. greater choice of wheel applications in an 18, greater choice of tires and overall less expensive...
As for the argument that a 17" wheel is lighter than an 18" . That is highly dependent on the quality /brand of wheel to be fitted. There are many aftermarket 18" wheels that are far lighter than oem 17" wheels.. That is an easy solution.

For my S4 I currently run oem 18x8.00 shod with 245/40 Conti DW's. This summers set up will be 18x9.00 with 255/35 Conti's. ( 8.5 width is also an option but 9.00 is the preference. )

[Quadfreak]

Not sure where your thoughts on this are but ...
18's are oem for the S4, reducing the wheel diameter and increasing the tires profile will decrease handling response. As for the brakes.... Why ??? If you put 17" rotors which I think are 280 mm that is a smaller circumference which will (1) increase heat retention and (2) may not even function properly.

Just for the record, the 17Z caliper uses a 330mm rotor not 280mm. Only a 15mm reduction in size from stock.

[LINDW4LL]

I know the 18z are a popular upgrade but I don't want to go to 18in wheels. The rotors with the 17z would be smaller then stock but I would think you would still get the performance benefits of having better calipers.
What is everyone's thoughts on this?

Why are you averted to running 18" wheels? Just curious.

[B5man17]

I'm not against running an 18" wheel, but I like the added sidewall you can get with 17" wheels. I'm running ohlins suspension with 800lb spring in the front and 1200lb in the rear. Like most people I want to daily drive my car when I'm not tracking it, but its a harsh ride when you don't have a lot of sidewall. As some people said above about the loss of response with running 17s, I don't feel it at all it does not understeer anymore then if you were running an 18" wheel in my opinion.