Does anyone have any idea how much of a difference say a 24lb. wheel would make versus a 20lb. wheel in terms of performance? I think the stock 16x6 wheel on the SHO is something like 18lbs. Now I know the lighter wheel is optimum, but I’m looking for wheels in the 17x8 size and have found a few nice choices, the heavier wheel is less money…but at what cost? This car is my daily driver and honestly I’m mostly interested in the looks and handling over quarter mile times. Links would be appreciated if anyone has seen any back to back test from a reputable source.
Lighter wheels speed up and slow down faster and they lower unsprung weight. For a DD i wouldn’t be too worried but from a performance aspect lighter is better. It’s all a rotational weight thing.
IT’s a simple matter of math. You need to figure out the rotational weight difference between the two types of wheels you are looking at. Without going into the math formulas/physics, cliffnotes = the more weight and mass you have rotating, the more work your engine has to do to accelerate and decelerate the mass, and the more work your calipers have to do to stop them from spinning. This is not only your wheels, but your rotors are factored into the equation as well
If you are all about racing performance, obviously the less mass you have to rotate, the less work for your engine and calipers, and the faster you can go.
If this is just for everyday driving/street racing ( :gay: ) as long as your wheels don’t weigh more than your stock wheels, you will be just fine.
You will be hard pressed to find a website with this stuff (I could be wrong). It’s all proven in the math (physics). So either you do the math, or you don’t.
If you are interested in the math, then we can get to it. IF you just want to buy some wheels for your car, and don’t care too much about rotational mass, then just use your stock weights as a guideline. Try not to go over, and if you can get less weight for your money, then go for it.
20% is a huge difference, especially on a bigger diameter.
It also matters how far the weight is from the the axis of rotation - 24lb as 15" wheel is easier to get going than 24lb 19" wheel…
Not sure if everyone understood what I was asking…I do know that heavier wheels will translate into worse performance. Rx3, I’d be interested in seeing some math…
Here’s a writeup on tirerack showing 3 combo on a BMW going from 38.5lbs. to 48.5lbs and comparing/contrasing… http://www.tirerack.com/wheels/tech/techpage.jsp?techid=108
Also, need to make a quick correction. The wheel I thought was 20lbs. is actually 22lbs. I weighed my 245/45/17 tire and weighed a stock size tire (215/60/16) and they were nearly identical. So I’m looking at adding 4 lbs. per wheel/tire combo…but getting a much larger contact patch…not sure how much that helps/hurts.
Again, it is little tough to predict exactly, because it matters how the weight is distributed around the wheel+tire combination.
Yeah, I know…I like to theorize and wonder about stupid things like this. The handling of the car will probably outweigh any losses in the straight line. Also, we’re talking about a high 14 second car here so it’s not like it matters much.
Mike, you won’t notice much difference. The handleing increase with a greater contact patch and shorter sidewall will be > than any loss in acceleration. My guess with out getting to technical in advanced quantum physics… about .15-.20 difference in 1/4 mile times. Negligable IMHO.
The general rule of thumb is that taking 1 pound off the wheel is like taking 10 pounds off the car, as far as straight line acceleration is concerned. So 4 wheels that each weigh 4 pounds less would be like taking 160 pounds off the car.
Source: http://www.sentra.net/tech/garage/suspension.php
A quick check of my old dynamics book confirms…
…that I have better things to do than run through force balance equations of a system consisting of rotation and translation such as a wheel with torque being applied and rotational inertia resisting as well as the translational intertia of the car resisting…
damnit i wrote up a long description on this, basically for every extra 1.5lbs of rotating mass it turns into a loss of about 1hp, and i forgot the de-acceleration effects in torsion force on your calipers. Damn vertigo for going down
I would have guessed more than 1hp.
i think i have that backwards, it might be 1lb=1.5hp, but that is also per wheel, i need to see if i posted this on a bored that is still up
you would need more info…it’s also dependent on your moment arm (or how far the mass is away from the center of rotation). You could have a larger diameter wheel at a lighter weight and be equal to a heavier wheel with a smaller diameter.