i have searched around to find the weight of the stock wheels, but never found a good anwser. does anybody know what they weigh. and assuming that they are big ol fattys will putting a 14lbs 17" ssr wheel slow my quarter mile time? also would a 8" wide wheel with 225's fit under the wells and not rub? and does any body know a place that sells volks for a pretty good price. they may be aut of my leauge but i thought i would find prices. thanks guys.
-Josh

oh yea one more thing i forgot to ask, does any body know of any good light weight cheaper wheels.





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14 lbs is pretty light I am thinking for a 17" wheel. Most are around 20 lbs unless you get into the real expensive racing wheels. Im pretty sure you can fit 225s on your car.

yea 14lbs is an educated guess. in scc they weigh 18x8" ssr competitions at 14.6 lbs a peice. so a 17x8" would have to weigh less than the 18's. probably less than 14 but its better to stay on the heavy side, so i dont over estimate performance. for all four its about $1500, so yea they're pretty pricey, but worth it if they help handling and dont hurt my acceleration.
-Josh




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weight isn't what slows you down. it's the diameter of the wheel. you lose acceleration because the wheels have to spin more to make the same distance. the upside is more top speed. the only way wheels could make you faster would be to get the same exact size wheels only lighter

Actually, it's the diameter of the tire and the change in the moment of inertia that make the difference. Larger circumference wheels move more of the weight to the outer edge of the wheel/tire combo thus increasing your moment of inertia (effective load the engine sees due to your wheel weight). However, a light 18" wheel could perform the same as a heavier 17" wheel. If the weights are close, the difference will not be great, but it's something to keep in mind if you're really concerned about it.

This is all assuming the outer tire diameter stays the same which can basically be done if you pick the right tire for your wheel.

yes..225 will fit under. i have 18x8 w/ 225/40

^^^it's impossible to get the diameter of the tire on the wheel exactly the same because the heightof the tire is measured in percent. and not all tires of the same size are the exact same height.

yea the tire diameter isnt going to be exactly the same but if memoy serves then 225/45-17s are .9% bigger than 250/55-16s, so not enough to change acceleration. and mkerley i realized that alot of the change comes from the mass of the wheel moving farther out and thus more rotaional inertia. but was thinking that moving the wheel diameter/ mass out one 1/2 inch, and reducing the weight probably by about 10lbs or more then they would equal out.




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oops i meant 205/55-16s
-Josh




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I just put 225-50-vr16's on my car with a momo 8 inch wide wheel, and I had to "roll" the rear of my car. It was rubbing when I went around a heavy corner. Just "normal" driving wouldn't get em to rub but when I try to "play" a bit it will rub. I do think that it is partly due to the face that I have FACTORY struts still from 95 and I'm lowered. Soon to be H&R Race springs and tokiko adjustable's.

Tirerack has a chart that shows each tires exact tire diameter and how far from stock size it is, very helpful.

>^^^it's impossible to get the diameter of the tire on the
>wheel exactly the same because the heightof the tire is
>measured in percent. and not all tires of the same size are
>the exact same height.

True, but like joshacu said, the difference is miniscule. My stock tire was 205/55/16. The outer circumference is 78.1564". My 225/40/18's have a circumference of 78.811" which turns out to be 0.84% difference. That means when my speedo says 80, I'm actually doing 80.6 mph. Our speedo is not nearly that accurate, so the difference is negligible.

As long as your tire size is pretty close, the gains/losses from a difference won't be seen on the dyno or the track. However, the difference from the weights of the wheel/tire combo due to size of wheel etc. will be seen in both places.

Matt

I think the stock weight of the normal 16's is like 20lbs SO your car should be a little faster despite their larger size.

Another thing to think about is when i went from 16s to 17s it made my car a hell of a lot more stable. With the 16s on around 100- 110 MPH the rear end of my car would become squirly. Almost scary as a matter of fact. I thought it was funky turbulence of my wing since I have the high one. But I went to the 17s and that went away. So in a sense i was able to go faster because the car was more stable and I felt a lot more ocmfortable doing it. Dunno I re-read this post and this came to mind.

Larger diameter wheels will reduce your final drive ratio and make your car a bit slower but I'd think a 1% difference is not going to make that much of a difference at all. Also, heavier rims and tires will make your car slower, but this is what slows you down the most: rotational inertia

It takes energy, work, power, whatever to get a wheel to turn. The more weight on the outside diameter of an object that rotates, the more energy it takes to get it to spin.

Simple experiment. Sit in a chair that spins around. Put two 5 lbs weights in your lap. Spin around while sticking your arms out, it doesn't take much effort to get you to spin. Then, hold the 5 lbs weights in each hand and do the same thing. It takes more effort to get you to spin at the same speed.

The outer diameter of rotation (your hands) remained the same, but you put the weight that was in the center of rotation (the weights on your lap) to the outer edge of rotation (your hands).

What's that got to do with tires? Well, a 225 tire will take more effort to spin than a 195 tire. Yes, lighter wheels and tires are good (less unsprung mass, and less weight is always easier to move around than more wieght) but where that weight is makes the difference. Wide, heavy treaded tires will slow down a car with no power (i.e. my car and our cars) more noticeably than a car with more power.

Hope that helps out

well put, I remember doing that same experiment in HS physics :)

>Another thing to think about is when i went from 16s to 17s
>it made my car a hell of a lot more stable. With the 16s on
>around 100- 110 MPH the rear end of my car would become
>squirly. Almost scary as a matter of fact. I thought it was
>funky turbulence of my wing since I have the high one. But I
>went to the 17s and that went away. So in a sense i was able
>to go faster because the car was more stable and I felt a
>lot more ocmfortable doing it. Dunno I re-read this post and
>this came to mind.

more contact patch. in motorcycle terms this is called trail. when suspension allows more contact to the road.

plus i'm sure you have much better tires now.

but to finally answer the question. yes bigger wheels will always make you slower, whether it's from the weight or the diameter.