The topic is weight of wheels and how it relates to performance. I own a 04Z and I've tried really hard to keep the weight down on the Z with the performance up grades. The question is unsprung weight and the rolling mass/inertia/momentum which robs HP. Here's what I'm contemplating, switching my C5Z OEMs for C6Z OEMs. The research that I have done has revealed some flaws in my quest for more rubber under the rear(on a budget).
The facts:
C5Z Alcoas 17x9.5=19lbs
18x10.5=21lbs
C5Z tires Bridgestone Potenza RE760 265/40R17=26lbs(front tires)
Bridgestone Potenza RE760 295/30R18=29lbs(reartires)
Totals=C5Z fronts W&T=45lbs and rears W&T=50lbs per side

Now for the what I was considering
C6Z Speedlines 18x9.5=22lbs
19x12=26lbs
C6Z tires Kumho XS 275/35R18=28lbs(front tires)
Kumho XS 345/30R19=41lbs(rear tires)
Totals=C6Z fronts W&T=50lbs and rear W&T=67lbs per side

So the difference being; Going to C6Zs is an added 5lbs (x2)per side in the front and an added 17lbs in the rear (2x)per side. For a grand total of 44lbs to convert to C6Z OEM Speedlines. That seem ridiculous !!

So 44lbs of rotating mass is equal to 4-6lbs of static weight. We will take the average of 5lbs x the 44lbs gained = 220lbs. WOW. Thats not acceptable.
My car makes about 430 N/A and 600 on spray at the tire, and only weights 2975lbs.
So my question is will I feel this in the seat of my pants ?? The power loss to turn those big lugs is what I'm referring to. And does anyone have experiance with what I'm talking about or input to help ? I take it to the drag strip about once a month and road coure it about twice a year. But I'm not into hopping up the car just to turn around and slow it down with a bad choice of wheels. Not to mention taking a country mile to bring it to a stop.
I'm really looking for hard facts or peronal experiances. For example; if my car runs consistant 10.99's (N/A) could it potentially drop to 11.30's or something like that ?? By just changing the wheel and tire combo. The change is mainly for lack of traction on the street and the 19x12's look sick with the L5 fenders.
Again any input is much appreciated. Thanks..

 

Yes, you will notice the difference, especially in cornering. After having custom wheels I ended up back on stock wheels and felt much better behind the wheel.

 

I'm surprised your not having traction control issues because the rear tire is not sized correctly at 295/35/18. Maybe you made a typo ?

I have no drag times. But I can say for 100% accuracy that you WILL feel a difference in how the car drives and handles. 4 yrs ago I put on a china crap set of wheels. I never know about the weight issue (I do now). The car felt EXTREMELY sluggish, turn in was diminished, Car accelerated slower, It just felt like I was dragging a brick behind the car. I honestly felt an immediate difference when I first let the clutch out pulling out of my driveway. It felt like it engaged differently. After a week I pulled the China set of wheels, and I weighed them on my bathroom scale. The rears were 11lbs MORE than stock (each). I did not weigh the fronts, but I knew I basically just added about 40lbs of rotating mass. . I put my stock Z06 wheels/tires back on and it honestly felt like I got a seat of the pants performance boost.
I got all my performance back. I then felt sick to my stomach that I spent so much $$ on wheels/tires just to slow down my performance car. I sold the heavy wheels that next weekend.

I am "VERY" in tune with the performance of my car. I only weekend cruise with it. You going to get varied answers on this. If you are "In Tune" with your car like I am, then you will for sure feel a difference.

Toque

 

Yes, typo 295/35R18 is correct.

There are a lot of great points made here. Just to clarify, I have track wheels and tires. This set up is stricly for my street adventures . I'm just not wanting to slow the car down for the street. But needing more traction for the spray !! Hints the 345 with a sticky street tire. And please don't mention DR's because I enjoy the topend handling as well. But thanks again ..

 

tire width has little to do with grip.

But softer rubber compounds do.

Look at Nittos or Toyo tires.

 

I was going to mention CCW Classics but then I saw the word budget in your post. While these are not a budget wheel, well compared to most aftermarket forged wheels they are, they are your best bet. I honestly think you need to stick with a 17 or 18 inch wheel as well.

I've seen a silver Z06 on here with 17" black CCW Classics all around and it looked amazing. The 17's didn't look small or out of proportion at all. If I were you I would really consider staying under 19 inches. I'm not saying 19's don’t look great, because they do, but there not the best for performance. All things being equal an 18" wheel will handle and provide better traction then a 19" wheel.

 

CCW's are definitly in the future.

 

^^^^^^^^^^^^^