damn jon. You're making me want those kolors!

 

I've still got the old ones, if one of you guys wants them.

 

DTN, 19lbs wouldnt be considered very light for 15's, which is why we say 1lb/inch is considered lightweight, theres no confusion that way.

And, no, centrifugal (not centriugal) force doesn't multiply weight of rims at any speed, the rotational inertia of a heavier rim is slightly harder to steer because of the higher weight, slightly, but your power steering system wouldn't notice even with 45lb chromers

F=ma is the reason lighter wheels are easier to accelerate, same force, less weight, more acceleration.

and yah, the stock wheels are pretty heavy for 15's, i managed to stay the same weight with 16's and get the handling benefits, i'd like to get lighter rims eventually tho.

 

Look at it this way guys.

Stock rims are around 19.5 pounds.

My new ones and old ones were 15 pounds.

Thats' 4.5 pounds per wheel, or 18 pounds for the car that I saved, in ROTATIONAL weight. That's a LOT.

Now you can also do the same with the tires. I'll weigh one of my current spares, someone go weigh one of the OEM sized tires. I'd estimate about a 3 to 4 pound difference at least. Let's say 3. That's another 12 pounds saved.

Then you have the compressed air, MUCH more of it in the old tires than the new ones.

See where I'm going?

Not even doing the air, that's 30 pounds of rotational/unsprung that I've saved.

 

Actually, they are spinning so it's not only the mass what's important, it's also how it's distributed. It's what HKN was trying to talk about, it's called moment of inertia. If you have two wheels of equal weight, but one of them has most of its mass concentrated in the middle, while the other has most of the mass concentrated towards the exterior, the second one would be way harder to accelerate (it has a much larger moment of inertia). The relevant equation is similar to F=ma, but it's actually T = I*alpha, where T is the torque needed to accelerate an object with moment of inertia I with angular acceleration alpha.

You can think of every tiny piece of material in the object as a separate mass. The torque which you have to apply to make that mass spin around with a certain angular (rotational) acceleration is proportional to the mass times the SQUARE of the lever arm (so the weight distribution makes all the difference). You can read more at http://en.wikipedia.org/wiki/Moment_of_inertia

The total mass is only important from the general weight point of view (lighter rims -> lighter car -> faster acceleration), but this only makes a subtle difference in comparison with the rotational inertia which needs to be overcome.

 

oh i agree totally, DTN just likes to make physics faux pas.

He was insinuating that the rim actually gets heavier under rotation, and im aware of the moment of inertia and weight distribution of a rotating object, which is the reason figure skaters spin faster with their arms tucked in.

F=ma is generally acceptable enough description when your just talking in general terms and your not doing an engineering calculation.

 

physics = teh Poo

these=teh Shyte.

I want to see a tiburon with them shoes. Has to be right color..

anywho, nice shoes Jeremy! wanna f/./ hahahaha nv,m...

(you should do what I do and get a pair of track rims/tires/rotors/pads) Takes about an hour before race day to swap em all.

 

when i said "factory spec" i mean the size of the rim, not the weight. the factory weight can go to hell lol. it's not that i don't like anything aftermarket, i don't like anything that goes against what the original intention of the deisn was. there are ferraris that look like shit, and there are bodykitted ferraris that look like calypso.

case and point: i always thought the 575 was kind of ugly. it's uneven flat shape and hair clip rims. looks like a normal car.

Novitec Rosso turned that completely around and made it one of the most beautiful ferraris ever built.

a little doing a lot. the bodykit flows with the car, looks like it was made with the car. the rims are godly. everyone will still look at any 575, but everyone will wet their pants when they see a Novitec. My point with this is why would anybody turn down a little "mmmphhh yeah" from onlookers... ? I certainly don't.

i've been such a critic always but understand it's in my nature. it's not that i don't like them, i think they're just ok and not inspiring. i don't mean to insult you or anybody just by saying what i really think. that's ok that everybody on here is different and has their own alternating personal appeal. i just like exotic cars and always think in terms of flash and design, what makes classic, what makes history, what inspires kids and what designs remind old men of their teens. combined beauty + function. if you think it's beautiful, i praise you. iif people don't like my rims or my car, i'll accept it and did it for the same reasons you did however i've noticed people who don't like my car don't like red ferraris.

a good example of what i'm saying is mad_johns old green tiburon, compared to the way it looks now. his old look was purely personal and performance. he got compliments (except the wing). nobody except me didn't find it attractive. it looked decent, but the new look. love.gif love.gif love.gif sport11.gif eek.gif slomo.gif hail.gif banana2.gif makes 99% of people drool their shirts and frankly i don't think he lost anything if much at all from his previous setup.

and dtn and alex01 brought it up, centrifugal force. but we've had enough of those arguments before and nobody here is paid to or has certificates to argue that but i will say you can have 19 pound 15's and 19 pound 22's and the 22's will make your car slower. that's my point defined by physics. that is a compliment to you for choosing your size red z.