would a 17 slow me down?

[rs_1101]

how much would a 16.5 lb 17" rota attack set slow me down!? does anyone have a rough idea?

[Burgh]

Compared to the stock wheel that weighs >20lbs (from what I've heard)? It wouldn't slow you down at all.

[EP3inRI]

Originally posted by rs_1101
how much would a 16.5 lb 17" rota attack set slow me down!? does anyone have a rough idea?
No, if anything it may help you out. The stock 15" rim is about 19lbs, so you would shave a little weight there, but depending on the size you choose for your tire, you may gain some back and break about even. But it shouldn't slow you down and you'll look good too.

[Btrthnezr3]

The lightweight 17's will help save a little weight (especially compared to some other 17's)...but you must take into account rotational mass...read this thread. (http://www.ephatch.com/forum/showthread.php?threadid=27984)

The rims may slow you down a tad, but probably not by much...and the cornering ability/stability will be greatly improved. If you drag race, 15's or 16's are better...autox 16's usually (sometimes 17s)...and for daily and bling 17's are nice. Also, take into account the price of tires and some of the issues with 17's (ie potholes, etc). A search might help you out a bit too. Good luck!

[SiGuy]

I've heard our wheels are 22 lbs apiece-pretty heavy. Stock tire and wheel are about 40 lbs. As long as you stay well under that that rotational mass should'nt be a prob. Personally i'm gonna go with 16's at 13 lbs.

[Vertigo]

Eventhough you might be running a lighter wheel than the stock unit, rotational mass plas a major part. Sence a 17 inch wheel is larger than a 15 inch wheel, the majority of the weight(mass) of the wheel is moved to the outer part of the wheel. This is where Newton's 3rd law of motion comes into play.

[glw]

Originally posted by Vertigo
Eventhough you might be running a lighter wheel than the stock unit, rotational mass plas a major part. Sence a 17 inch wheel is larger than a 15 inch wheel, the majority of the weight(mass) of the wheel is moved to the outer part of the wheel. This is where Newton's 3rd law of motion comes into play. but the tire is the outermost weight, not the wheel.

could you briefly explain Newton's 3rd law of motion for us and how it realates to increasing the radius of the wheel by .5" (for 16" wheels) or 1" (for 17" wheels).

[chet]

Originally posted by EP3inRI
No, if anything it may help you out. The stock 15" rim is about 19lbs, so you would shave a little weight there, but depending on the size you choose for your tire, you may gain some back and break about even. But it shouldn't slow you down and you'll look good too.

SOmeone has weighed them, they're a little more than 20, like 22.5 or so. THey're pretty heavy. ANy reduction in weight will be benenficial. . .Also as far as the rot-mass theory, I've talked with a few competitive drag racers about this topic, and they felt that as long as the new wheel/tire combo was not taller and heavier--you would benefit.

[EP3inRI]

Originally posted by chet
SOmeone has weighed them, they're a little more than 20, like 22.5 or so. THey're pretty heavy. ANy reduction in weight will be benenficial. . .Also as far as the rot-mass theory, I've talked with a few competitive drag racers about this topic, and they felt that as long as the new wheel/tire combo was not taller and heavier--you would benefit.
I'am a mechanical engineer and yes I know about rotational inertia, but I don't wanna get too far into Newtonian Physics. GLW, even though you are concentrating the mass further out, if there is less of it, it will still be slightly benifical. But I'm sure when RS_1101 asked if anyone had a rough idea he didn't expect anyone to quote Newton. Also drag racers choose a smaller rim so they can save weight and have a meatier sidewall. I have a spare set of Si rims and I weighed them on my bathroom scale at 19.5 lbs. It may not be calibrated to the standards for a discussion about Newtonian Physics, but it gives me a rough idea that I ate too much over the holidays.
RS_1101, I would get the wheels. They look nice on an Si, they will probably help more than hinder as long as you stay around the stock overall tire diameter. Plus, you'll get the added benifit of a wider contact patch and less squishy sidewall.

[rs_1101]

yea i think ima go for it. i actually got bored and calculated and approximate ratio of work needed to rotate the wheel one radian..
i assumed the bulk of the wheelwheight was at the lip then i used a couple highschool equations such as

(pi)R = .5 circumfrence
then i remembered work=massXdistance
so i did
(pi)15X19.5 = 292.5 work units
and
(pi)17x16.5 = 280 work units

so there you have it. mathematical proof that the 17 is easier to spin.

this is prolly alittle basic but i think its a good start.

[chet]

BTW, wanted to let you know I've had my Attacks for about a year and I dig em. I think I may get them powdercoated a diff-color, other than being tired of the color they're great.