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It's sound.

Posted by: Mirror|rorriM on 2002-11-15 14:16:11
Account #: 11167

In Reply to: I read the entire post. Twice now... posted by George @ BostonAudi on 2002-11-15 13:59:03

He calculated the kinetic energy of the car. This is a sum of the mass of the vehicle moving at a given speed, and also the rotational mass @ a omega of the wheels.

If you lighten the wheels by a given amount, you get kinetic energy Y. If you kept the wheels the same weight, how much mass would you need to remove from the car to get kinetic energy Y? That's what was calculated.

Mirror|rorriM
I've ridden a total of 52 days so far this season
I got to snowboard a total of 45 days in the 06-07 season.
I got to snowboard a total of 58 days in the 05-06 season.
I got to snowboard a total of 139 days in the 04-05 season.
RYAN SMITH ("GOLFRSI" or "BIADesigns") STOLE MY A-PILLAR. DON'T DO BUSINESS WITH THIS FRAUD

RYAN SMITH ("GOLFRSI" or "BIADesigns") STOLE MY A-PILLAR. DON'T DO BUSINESS WITH THIS FRAUD

My First Post

Thread:

A study investigating the effective inertial weight of wheels. Warning: technical in nature. - Toy_Guy 2002-11-15 12:38:48 (8165 views)

Craig 0wnz j000!! - Xr8edS4 2002-11-16 08:09:26 (930 views)

I just edited my post to add some clarification. - Toy_Guy 2002-11-16 06:04:34 (824 views)

you know what's funny - frank 2002-11-15 16:52:31 (1069 views)

The only variable with a wheel is the weight (within a given size) - this is not the case with tires - Mirror|rorriM 2002-11-15 22:20:29 (990 views)

Actually - squidix9 2002-11-16 21:43:13 (1558 views)

Those look mean ; ) - Singletrack 2002-11-17 16:25:40 (799 views)

That's what - squidix9 2002-11-18 05:37:05 (648 views)

That's a cool site, couldn't find the video though. - Singletrack 2002-11-18 07:17:19 (636 views)

Rat's - squidix9 2002-11-19 06:04:46 (608 views)

Yeah I saw the pics - totally nuts. How did you get into ice racing? - Singletrack 2002-11-19 06:59:43 (685 views)

I got into ice racing because - squidix9 2002-11-19 13:18:56 (725 views)

Very cool man, thanks for all the info : ) - Singletrack 2002-11-19 14:35:36 (489 views)

Other than being F*&^&!g cold winter is cool for racing - squidix9 2002-11-19 20:12:02 (542 views)

I looked into this. Toyo TS-1 is the lightest in a given size. Bridgestone S0-3 is real heavy. - PhoenixS4 2002-11-15 17:08:59 (1676 views)

And don;t forget, a 235 is about a pound heavier than a 225. - PhoenixS4 2002-11-15 17:39:23 (614 views)

but - BSOD 2002-11-15 17:07:09 (652 views)

Good point. I speced out my winter vs summer weight about a month ago and - Singletrack 2002-11-15 17:00:48 (776 views)

werd, and tires are cheaper than bling bling rims - frank 2002-11-15 17:02:27 (1233 views)

unless you're sensible... OZ SL's are light and well priced. - S4 from GT 2002-11-16 01:22:13 (926 views)

A little flawed on rotational inertia. You have to chop the wheel in a thin pizza slice... - Audiboy 2002-11-15 15:24:12 (1242 views)

I think that's what the modern world calls 'Calculus' ;-) - Mirror|rorriM 2002-11-15 22:16:30 (688 views)

woah...old man of the internet...aim# 9!?! and I though I;d been here a while - SwampGTI 2002-11-15 17:04:20 (697 views)

oops, nevermind, I just read George reply. - Audiboy 2002-11-15 15:26:39 (664 views)

Nice analysis ... - sj6spslvrS4sdn 2002-11-15 15:12:22 (635 views)

Sounds about right to me. I have always gone by 1lb unsprung equals around 3 times sprung. - Singletrack 2002-11-15 14:08:09 (605 views)

Is this in Engrish? - Ben AKA NUHuskyfan 2002-11-15 14:02:20 (575 views)

Don't forget the Moment of Inertia for the Brake rotors, etc... ;) - reefer_bob 2002-11-15 13:58:37 (793 views)

I think saving 16 lbs. on brake rotors felt like it saved me 19.2 lbs. based on this... - LCP 2002-11-15 15:34:14 (715 views)

I run - squidix9 2002-11-15 13:50:04 (732 views)

What size is the OZ forged wheel and what does it look like? - PhoenixS4 2002-11-15 14:08:55 (1075 views)

I've got a bunch of 15X7's and 15X8's - squidix9 2002-11-15 21:23:46 (971 views)

The analysis is valid for no loss of traction. A burnout has different dynamics. - Toy_Guy 2002-11-15 13:59:20 (562 views)

True, but my point is the ability to - squidix9 2002-11-15 21:19:23 (623 views)

OK!!! All fixed up with the sub/superscripts added in. - Toy_Guy 2002-11-15 13:44:17 (735 views)

You're a swell guy. =) - LCP 2002-11-15 15:21:38 (616 views)

I would stress in the beginning its a 10 lb reduction PER wheel/tire just to clarify - Stealth4 2002-11-15 13:34:39 (613 views)

So ultralight tires is where the smart money's at!! - RichmondS4 2002-11-15 13:28:41 (764 views)

so my effective weight loss, if i bought lighter wheels, doesn't justify my effective wallet burn. - Mr. Piggie(mike01s4) 2002-11-15 13:12:22 (808 views)

...and that's why manufacturers don't do it either... - LCP 2002-11-15 13:14:57 (820 views)

No - making the wheels *heavier* can aid fuel economy - Mirror|rorriM 2002-11-15 14:10:04 (759 views)

I think that's a stretch - stiles_s 2002-11-15 14:48:35 (637 views)

I know it's a stretch...it really depends on what the EPA uses for their test - Mirror|rorriM 2002-11-15 15:02:10 (557 views)

for mfg'ers, cost of a heavy/stong wheel << cost of a light/strong wheel - BSOD 2002-11-15 13:45:48 (718 views)

Please edit your post to include subscripts. It's permitted HTML. See Forum FAQ. - LCP 2002-11-15 12:56:39 (551 views)

why dont you do it :) - Stealth4 2002-11-15 13:15:25 (679 views)

Toy Guy did enough as it is! - Mr. Piggie(mike01s4) 2002-11-15 13:09:43 (629 views)

Thats close, but not quite right... - George @ BostonAudi 2002-11-15 12:55:16 (1001 views)

By pretending the mass was all at the radius of the wheel/tire, he gave the best case scenario - Mirror|rorriM 2002-11-15 14:05:19 (666 views)

Exactly, Jeff. I'm glad you follow the simple physics! - Toy_Guy 2002-11-15 14:15:39 (533 views)

I think the internet tuning business would die if we started scanning the books on our shelves :-) - Mirror|rorriM 2002-11-15 14:17:38 (531 views)

George, why don't you try reading my post in entirety before commenting? - Toy_Guy 2002-11-15 13:45:37 (620 views)

I read the entire post. Twice now... - George @ BostonAudi 2002-11-15 13:59:03 (724 views)

It's sound. - Mirror|rorriM 2002-11-15 14:16:11 (710 views)

Agree. I was thinking of acceleration and braking, not constant velocity when I posted above. - Audiboy 2002-11-15 15:33:13 (576 views)

The same math applies, regardless of acceleration - Mirror|rorriM 2002-11-15 22:22:48 (547 views)

Well, I'll back out in disagreement... - George @ BostonAudi 2002-11-15 14:29:56 (635 views)

Sorry, my terminology was misleading - Mirror|rorriM 2002-11-15 14:40:29 (598 views)

"how the car is driven" == AWD vs 2WD, not driver skill :) - George @ BostonAudi 2002-11-15 14:00:59 (1018 views)

That only affects dyno numbers, not the actual #s put down on the pavement - Mirror|rorriM 2002-11-15 14:11:18 (596 views)

george, he's calculating it as if all the weight was all the way - BiTurboBoy 2002-11-15 13:02:39 (762 views)

Right... I've always seen approx 4x equivalence... - George @ BostonAudi 2002-11-15 13:04:43 (772 views)

damn, engineering is hard to read without subscripts.... - BiTurboBoy 2002-11-15 12:45:02 (679 views)

You could be totally wrong and I would have no clue, but it sounds good =) - 2k2S4 2002-11-15 12:41:09 (548 views)

I read it on the internet.... ;-) - Mirror|rorriM 2002-11-15 14:18:17 (565 views)

It's not wrong, trust me :-) - Toy_Guy 2002-11-15 12:43:49 (631 views)

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