Wheel/Tire Weight

[wret]

Speaking of nitrogen, aren't NASCAR teams using it to inflate tires?

 

[Attack Eagle]

I am just going to use some rough figures here:

4560 rpm(engine) * 4th gear (1:1) * end drive 4.56 = 1000 rpm

wheels do spin at high rpms

and since someone here did point out that the Force required is mass * acceleration angle squared any increase in mass at the wheels has enormous effects on acceleration.

dropping 40 lb at the wheels is like adding horsepower. Imagine dropping 40lb off a flywheel? How much easier would it be to accelerate, or to brake while in gear?

10 lb per wheel is worth doing if you can afford it. less than 4 probably not.
Stock 17 rims are 25 pounds for a GSX, Talons are probably 2 or more pounds heavier.
Anything 19 or under woud be considerable weight savings!

Going with a 17 versus an 18 has bigger effect as the mass of a "wheel" is primarily in the rim. adding an extra 1/2 " in diameter increases angular inertia as does the fact that the rim now has an additional 3.14 inches of diameter (more mass at the rim) and the tires also tend to wegh more in the larger diameters. Usually they are also 7.5 so another 1/2 thickness. Becuase they are generally used with lower profile rims they usually are of a thicker crosssection (heavier construction) in the rim itself also.

You might lose 1-2 lbs on the tire and 2-3lbs on the rim just by changing to a 17 in the same brand tire rim but same overall diameter
In my estimation anything 5lb or more is going to have a measurable impact in your glutteous maximus accelerometer.

16' are even better than 17s, but most street drivers prefer to stick with a 17 or an 18 because of asthetic and brake clearance issues, as well as the fact that 17/18 are practically a standard rim size nowadays. Weight is the only thing keeping me going from a 17 to an 18. Besides, with the proper wheel design you can gain an extra inch of "visual size" by choosing a wheel that terminates on the rims lip as opposed to inside the rim.
Enkei has a really nice designs that are light weight and subtle (ie not steal me like Volks)
Compare visually the RPF1 the RC5 and the ZR2 on the left side of enkeis page where they are all the same size picture and they look different sizes because of the way the lip design is...
http://www.enkei.com/High Performance.html
BTW my favorite rims right now are the RC5's just too expensive still... I think they are in 17x7 already and are only 17-18 lbs. I'll give up 1-2 lbs weight savings for style over the thinner and probably more dentable lighter wheels.

I don't know remember the physics but I do now from diving that 80 cubic feet of air weighs about 7 pounds. I don't think you have that much air in your tires. You could probably loose a couple pounds by filling your tires with helium but you would loose more by taking a laxative.

Volume of a gas follows boyles (sp) law
to increase the pressure w/o a resultant increase in volume (tire is fixed size) means that the amount of air does increase. MOre air equals more weight.
We are talking about pounds or even ounces here but yes, a tire at 0 psi 10 psi 50 psi and 100 psi would weigh different. they have different amounts of air in them.
Filling them with pressurized helium would still add weight. Helium only floats because at the same pressure as the atmosphere it weighs less. Adding more than 0psi (over atmospheric) of helium would add weight to the tire rim combo.
Nitrogen is used by race teams not to save weight, but because it is Dry (little to no water vapor). They require predictability, there are enough variables without adding another.


just my 1.02