# Folks, how do you meause or an equation to

1. Mar 28, 2012

### El1iP3S01D

find the mass or volume of a lamborghini gallardo wheel that measures 8.5 in width and 18 in height...

Can you help me with this? here's what i http://www.lamborghini.com/en/models/gallardo/lp-570-4-spyder-performante/technical-specifications/ [Broken]
Thanks for reading....

Last edited by a moderator: May 5, 2017
2. Mar 28, 2012

### hondaman520

due to your extremely vague question, I dont think anyone knows what your talking about.

Lamborghini wheels are like any other performance car wheels as far as i know. There are only subtle differences in mass or volume, mostly being the technique lambo used to apply their paint to the wheel. Aluminum alloy meaning its very lightweight, yet holds the durability of a typical heavy steel wheel. Many of the European (specifically italian) supercars show the same technique used to make these wheels as lambo. I'm not sure even a factory service manual would give you specs on the mass or volume of a wheel.

Why would you care to know the volume or mass of the wheel? There no way to even derive a formula for the volume because you don't have mass or density specs..

M=VD

i was however amazed to see that the lp 570-4 had a compression of 12.4:1 That is ASTOUNDING. I thought my Japanese shipped engine had a high compression with 11.1:1 (b18cITR) -most american cars wouldn't be seen with over 10:1 out of the factory

Last edited: Mar 28, 2012
3. Mar 28, 2012

### El1iP3S01D

@hondaman, i gave the height and width in inches to determine the volume or mass of the Gallardo wheel...as for why i want to know? because, i'm trying to derive the equation to calculate the mass of the wheel so that i can create a suspension for Lamborghini Insecta....That i'm modeling for a simulation...

4. Mar 28, 2012

### hondaman520

That is exactly my point. given dimensions of rim size and width isn't NEARLY enough information to get what you want.

That information alone would give you the volume of the entire rim including the 90% of volume that isn't taken up in the inside of the wheel. Those dimensions are used strictly for tire sizes and fitment to chassys.

If you were able to get the realistic volume of that wheel in the first place... you would still have to know the density as well, in order to find the mass.

as i was saying, you cant find mass without knowing density AND volume. Just as you cant find the volume without mass AND density.

If you have a more general question regarding the engineering of this suspension you care for, I should be able to help, i have a pretty solid background on this stuff.

5. Mar 29, 2012

### HallsofIvy

Staff Emeritus
You can approximate the wheel by a disc with radius 19 in. and thickness 8.5 in. That will be $\pi (19^2(8.5)= 9640$ cubic inches. Of course the actual wheel is NOT a solid disc so that is much too large but without more detail as to the shape it is impossible to be more accurate. To find the mass you need to know the density. You could look up the density of "aluminium" but there are many different "aluminium alloys" and the density depends upon exactly which one is used.

6. Mar 29, 2012

### hondaman520

^^ he is right, just as i was saying. Finding the density of an alloy wheel is almost never used in engineering of car/suspensions in the first place.. It might really hard to find out the density value of a lambo rim in the first place.

7. Mar 29, 2012

### Staff: Mentor

Actually, the diameter is 18", so the radius would be 9".

With that correction, you could calculate the volume of a solid disk, but that would be an overestimate, as the actual wheel in question probably has something like cast spokes, with empty spaces in between. Also, the thickness of the center part of the wheel would most likely not be as wide as the outer rim of the wheel.

8. Mar 30, 2012

### DaleSwanson

If I were you, I'd just try to find the weight of the wheel somewhere online. If you can't find the exact model you are looking for, try searching for the weight of a wheel with similar dimensions (also from a supercar). An email to the manufacturer might also work.

9. Mar 30, 2012

### chiro

You could also consider modelling the weight if you knew the density of the different components and used some kind of standard model in a computational package. Basically you have the same definition for density (i.e. p = m/V) but there is variation for different points and for different materials.

If this is for anything serious, I think doing the above would be a good idea.

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