So if smaller wheels are better for performance... why is it that Ferrari and Porsche

[neoprufrok]

are making bigger wheels for their "higher performance cars." Two examples being the new 997 Carrera S has 19" wheels in the front and the Ferrari 575M now has a "track package" that includes their ceramic composite discs and bigger 19" wheels.

Seems that the current thinking of smaller wheels = better handling may not be holding true? I would think that those companies would want smaller wheels if they thought the performance benefit would be better.

I'm also assuming that the wheels they are putting on those cars are fairly lightweight, thus negating the one big negative of having bigger wheels = weight.

[astris]

Don't Le Mans cars ride on 19's or 20's? Those cars are on incredibly light wheels. I can't remember the exact weight, but it is ridiculous.

[marked001]

I dont think it was ever said that smaller wheels handle better... thicker sidewall just means more deflection...

I think the performance issue with big wheels was always the added weight and if there was an increase in rolling diameter

[EVIL-AUDI]

Cause they all know that it's baller to roll 19" and higher

[JMG]

The weight was the biggest issue I guess. Plus if you had a Ferrari would you be rolling on 17's?

[mullarks]

You touch on the answer in your original question: brakes. You can't fit 15" calipers behind 17" wheels there is simply not enough clearance, hence you need bigger wheels to clear big brakes. And as others have mentioned bigger wheels aren't always that heavier ie. 17x8 stock S4 wheels weigh in at 28 lbs. per wheel while 18x8.5 (bigger and wider) SSR weigh in at 17 lbs. per wheel.

[D Piddy]

the unpsrung mass is the issue with larger wheels. these cars have incredibly light wheels therefore elminating the problem. plus, the wider the wheel, the better the performance, it creates a larger contact patch. but u can't have 15x10 wheels, it just doesn't work well, too much rubber and no tire companies make those. so these companies use large wheels with large widths that happen to be light in order to achieve max performance. plus the aforementioned brake issue and said ballerness of 19 and 20" rims

[Anthony]

Yup, all about the big brakes. Damn mullarks beat me to it!

[neoprufrok]

Originally posted by Anthony
Yup, all about the big brakes. Damn mullarks beat me to it!

Yeah, that's a good reason...

I've always known the arguments for and against, but now its starting to crystallize clearly why hi-perf cars go with bigger wheels.

I guess now I can use my Volks as my "track wheels" and get another set of 19's as my daily driver rims!!!

[Saturnine]

Your crazy meng!!

[tigabalm]

Originally posted by JMG
Plus if you had a Ferrari would you be rolling on 17's?

my thoughts exactly!!

peace

[voltronb5]

what they said about the brakes.. plus... with that much power, the companies can afford to sacrafice a little excess luggage for balla effect

[maxh2o]

Originally posted by voltronb5
what they said about the brakes.. plus... with that much power, the companies can afford to sacrafice a little excess luggage for balla effect

Its all Bout Big Brakes, Balla effect and Booty!

okay, I've had too much coffee today, ignore my last few posts.

[HotSauce]

If the wheel was too small, you would need one of the following.

1) Stiffer sidewalls. If the tire has to be taller, to achieve the same overall height, the added leverage caused by the sidewalls will put stress on the sidewalls. If the sidewall isn't stiff enough, the tire buckeles
2) Smaller tires. Alright, so if you want lower profile sidewalls, and keep the smaller wheels, you'll need to raise the overall gear ratio of the car, to attain the same top speed.
3) So say you did figure out the sidewall situation...What do you do about brakes? I suppose you could compression brake and pray, but in my opinion, the best way is to go with bigger wheels, with lower profiles, and some huge brakes.

[idrivemyself]

it all depends on your car's weight, stance, power output, and drivetrain. just take a look at any open wheel race car (F1, IRL, CART, etc).

[Thrawn]

Some of the WRC cars run 19"s on tarmac...

[RippleChip]

Exactly, and all the touring cars that have huge tucked rims.

The wheels and rims they use are super lightweight though, so it helps and then they cram a massive brake under there. Can't complain with that combo.

[neoprufrok]

Originally posted by Saturnine
Your crazy meng!!

It's all your fault mang.

I need to find some blacked out rims at 19"... haha.

[Hutash]

It is all a compromise. Side walls, weight, brakes, looks, horsepower, etc, etc, etc.

The overall trend is to go with bigger wheels for the aesthetics. How many people were rolling on 19" wheels five years ago?

[foofighter]

well as mentioned it's dependent on the racing formula...open wheel racing they're running 15x10 or so w/ stiff ass sidewalls where as in the sedan type racing teams go w/ bigger wheels for less sidewall deflection and the ability to run bigger brakes. but some of the racing series are spec class where they dictate max wheel and tire sizing so yah.

But the materials they use are crazy magnesium alloy etc superlight shiet

[rbt]

Just remember though, even lightweight materials won't defeat the laws of physics. Even if you had, say, a 19" lightweight wheel that weighs the same as a given 17", the 19" has a higher Polar MOI due to diameter. it will resist acceleration/deceleration more (all other factors being equal). whether it's enough to notice? depends, I suppose. In a Vette Z06 w/ all that torque probably not!

[foofighter]

having a big wheel can also have a positive affect going into the corner as you can carry more speed in due the "fly wheel" affect of the bigger wheel no?

[Hutash]

Originally posted by foofighter
having a big wheel can also have a positive affect going into the corner as you can carry more speed in due the "fly wheel" affect of the bigger wheel no?

Yes, but it is also harder to stop (i.e. slow down) and to get rolling again. Hence the need for bigger brakes and more horsepower.

[neoprufrok]

Originally posted by Hutash
Yes, but it is also harder to stop (i.e. slow down) and to get rolling again. Hence the need for bigger brakes and more horsepower.

Well I got the bigger brakes coverd.. now for the POWER... hahaha.

I think the other thing is the feel and response of 19" sidewall is much better than a 17" due to the soft sidewalls on 17" tires. Also, the contact patch is smaller on 17" vs a 19" wider rim.

Magnesium alloys... when are we going to get this technology?

[foofighter]

not DOT legal...you can only have X amount of magnesium in the alloy mix any higher and it wont be road legal

that's why when the BTCC was big in the late 90's w/ the fwd sedans carrying your speed into the corners was critical...scrub off too much speed and you kill your exit speed.

[voltronb5]

Originally posted by maxh2o
Its all Bout Big Brakes, Balla effect and Booty!

okay, I've had too much coffee today, ignore my last few posts.

you talkin about the 3 B's of car modifying? btw u forgot one more B.... ahah

[Mr.Black]

well all the answers were touched on it but in one word. Technology. forgeing has made bigger rims stronger and lighter than ever. and wheel strength is an improtant factor on a 150+ mph car. the Lil 15s on a ferrari 308 are super strong. tires have also come a LONG way in 10 yrs and they played a big part too. lastly style. image is probably the number 1 reason for most porsche and ferrari purshases (unfortunatly not performance). and, yeah 200k cars w 17s... just not cool.