19's effect
 

how much will the 19 inch sport package wheels on a 05 g35 affect 0-60 and 1/4 mile times?

Not sure exactly, but my 19's vs. my 18's is worth 3 to 4 tenths loss for me.

why is that? isnt it lighter?

Weight isn't the only factor to consider. You also have to remember, inertia plays a bigger factor when dealing with drag racing...you've taken the outer wheel and moved it out an inch...best example I can give you would be...take a skateboard wheel and a wagon wheel and tell me which one would spin up faster with the same power applied to it? It takes more power to spin the wagon wheel because the canter of inertia has been moved outward.

You may be right, but when I first drove my new one with the 19"s vs. 18"s the car not only felt light on its feet, but faster b/c the wheels weigh about 25% less.

I have no proof that it is faster, it just feels way easier for the engine to spin the wheels, plus the suspension is better.

Maybe there are ECU changes for the 2005s. There sure are differences between the '03s and '04s. Randy is right though. I took a long hard look at aftermarket wheels before I decided on 18" BBS. Yes, the 19s look sooooo much better, but I wanted my wheels to be an actual performance mod and not a exterior mod. Therefore, when I kept the same wheel diameter as stock and actually widened the wheel and tires, but didn't gain any weight, I made the car quicker. This was evident when I first put them on. I didn't think shaving 3 pounds off the rears and 6 pounds off the fronts would matter, but it does. You also have to take in consideration Randy's analysis. The 18" RGRs are 9.5" wide and have generous rear lip. If I had power to spare (FI) I would get the 19s.

What are these ECU changes everyone speaks of between the 03 and 04 models?