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Effects of Wheel Size/Weight on Performance

Old 08-22-2005, 11:46 PM
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Originally Posted by takahashi
You can be my Mazda salesman. I am sold on the 3! :D

Oh my love to do the drifting on the 17".... LOL

Must go and test drive the 3 in the weekend then.
haha, well i love my 3, best investment i made, saves me on gas too which is another reason i love, but other than that haha must be fun to drift, one of these days i'll do that, but im sure once u drive that 3 u'll never wanna leave till u buy one, thats how i was when i test drove one, good luck
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Old 09-09-2005, 10:46 AM
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Not to go too far off topic...

But technically you can get 6's cheaper then 3's currently. The 3's tend to have little negotation (they sell really well), while the 6's have some crazy negotiation rooms.

Some individuals have recently gotten (v6) 6s MTX's (NEW) for 16k with employee pricing (some dealerships offering it) and about 3k in rebates.

And if it matters, even after being out a year longer then the 3, the 6 still has less MRI's and TSB's. The dealers don't call it the TSB3 for nothing!

Still a sweet zippy car though. Just make sure to get an 05 or 06 to skip alot of the inital issues. If you are getting a 6s ATX, make sure to get an 05 with the 6spd ATX to avoid all the inital problems with the 5spd Jatco ATX.

Last edited by crossbow; 09-09-2005 at 10:49 AM.
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Old 02-07-2006, 11:51 PM
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Great thread manz~
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Old 05-31-2006, 10:19 PM
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hey i gots a question... will my 225s fit on a 18.5 rim??? i got some new rims and wanna use the stock tires. havent been able to search this....
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Old 06-01-2006, 02:26 AM
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you mean 8.5? Yes it would. But ideally you should go with a 245 tire.
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Old 11-01-2006, 11:09 PM
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Smile Winter weight.....

Just put the "snows" back on, and noticed that they were noticably lighter than the summers, so got the scale out.....

Summers (stock Bridgestone RE040, very worn) on stock wheel - 50.6 lbs.
Snows (new Toyo Garit HT) on cheapo-cheapo 17" FRD rim - 44.6 lbs.

Wow, 6 pounds per wheel, that's huge!

S
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Old 11-02-2006, 02:03 AM
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did someone with both OEM 16'' and 18'' wheel tried launching them and get the 1-100 time?
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Old 12-01-2006, 08:07 PM
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Originally Posted by cretinx
You guys worry too much about a few pounds here and there.

From my roommate who is a professional drag car builder (for Inline Pro) "If its a street car, don't worry about weight, worry about making power".
I'll just take a wild guess here and say he's an American.
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Old 12-02-2006, 07:57 AM
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Are there adverse effects of increasing the front tire width too much? Like increased required turn in force?
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Old 06-15-2007, 08:02 PM
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Originally Posted by crossbow View Post
I recently updated the orgy of unsprung weight links and decided to share it with a variety of forums. Feel free to keep, chuck, yell at, or do whatever you want with it. I figured since it took so long to gather all these damn links, it might be worthwhile sharing. Hopefully this won't offend anyone. Its just an orgy of available information for those interested in investigating it.

Articles

Size Matters
http://www.wam.umd.edu/~greghess/sizematters.pdf

Finding Free Power
http://www.nerocam.com/SCC_TAPnew.asp

Bicycles and Unsprung Weight
http://www.softride.com/bike/cornering.pdf

Fixing the 350Z: Why Lawyers Want Everyone to Run Staggered Setups
http://www.sportcompactcarweb.com/pr.../0404scc_350z/

Picking the Right Wheels For You
http://www.grmotorsports.com/wheels.html

Big Wheels, Big Trouble?
http://money.cnn.com/2004/12/15/pf/autos/w...day_big_wheels/

Wheel Weights Can Effect Your Vehicles Show and Go
http://www.tirerack.com/wheels/tech/...el_weights.jsp

The Danger of Dubs
http://www.edmunds.com/insideline/do/Featu...rticleId=104526

Automobile Ride, Handling, and Suspension Design
http://www.rqriley.com/suspensn.htm


Threads

17 vs 18, Drag Strip Comparison
http://forum.mazda6club.com/index.ph...0&#entry541857

How much does wheel weight really matter?
http://corner-carvers.com/forums/showthrea...rung+and+weight

Are 18" wheels and tires bling bling or a performance advantage?
http://corner-carvers.com/forums/showthrea...heel+and+weight

How much will 17" wheels slow you down
http://www.sccaforums.com/cgi-bin/ul...gi/topic/7/303?

Effect of Lighter Wheels?
http://www.sccaforums.com/cgi-bin/ul...gi/topic/7/301?

Bigger Wheels and Tires?
http://www.sccaforums.com/ubb/ultimatebb.p...ic/7/863#000004

Rotational Advice
http://forum.miata.net/ubb/ultimatebb.php?...=3;t=002795;p=1

If larger wheels are bad...why do sports cars have them?...
http://forum.miata.net/cgi-bin/ultimatebb....ic;f=3;t=005169

Wheel Weight, Who Cares?
http://forum.miata.net/cgi-bin/ultimatebb....ic;f=3;t=007412

1 Lb of unsprung weight =?? Static weight
http://forum.miata.net/cgi-bin/ultimatebb....f=3;t=006390;p=

Wheel Weights....Can They Make a Difference?
http://forum.miata.net/ubb/ultimatebb.php?...t=010655#000000

33.5 lbs/Corner Too Heavy??
http://forum.miata.net/ubb/ultimatebb.php?...t=010570#000002

Don't Small Wheels Mean Heavier Tires?
http://forum.miata.net/ubb/ultimatebb.php?...t=010479#000009

Whats With Huge Wheels?
http://forum.miata.net/ubb/ultimatebb.php?...t=010436#000002

18" Wheels too big? Take a Look!
http://forum.miata.net/ubb/ultimatebb.php?...t=008412#000031

I'm Finally Completely Convinced About Lighter Wheels and Tires
http://forum.miata.net/ubb/ultimatebb.php?...t=010379#000000

Do Wider Tires REALLY Provide More Traction?
http://forum.miata.net/ubb/ultimatebb.php?...t=010206#000034

Unsprung Weight 101
http://forum.miata.net/ubb/ultimatebb.php?...t=010206#000034

Unsprung Weight Effects Performance?
http://forum.miata.net/cgi-bin/ultimatebb....ic;f=3;t=008986

WO! The Joy of Lightweight Wheels!!!!
http://forum.miata.net/ubb/ultimatebb.php?...t=010108#000033

0-60 simplified wheel physics and garfield's wheel test
http://www.mini2.com/forum/showthread.php?...3730#post279748

Spreadsheet blows lid off lightweight wheel debate!!!
http://www.mini2.com/forum/showthrea...threadid=14738

Lightweight Wheels
http://www.mini2.com/forum/showthread.php?...unsprung+weight

In Defense of 17's
http://www.mini2.com/forum/showthread.php?...unsprung+weight

16 or 17 Inch Wheels?
http://www.mini2.com/forum/showthread.php?...ht=wheel+weight

18 or 19 Inch Wheels?
http://www.mini2.com/forum/showthread.php?...ht=wheel+weight

Effects of Wheel Size on Acceleration (TimeSlips)
http://forum.mazda6tech.com/viewtopi...t=1762&start=0

6tech Article
http://www.mazda6tech.com/index.php?option...id=16&Itemid=32

Wheel Weight and Performance
http://forum.mazda6tech.com/viewtopic.php?...der=asc&start=0

Some Wheel Weight Sites
http://www.wheelweights.net
http://www.wheelspecs.com
http://www.miata.net/garage/garagetires.html

I just finished reading through most of the links, VERY VERY helpful. Thanks crossbow for taking the time to find and put all this together!
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Old 06-28-2007, 12:52 AM
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This is really helpful with all the links and articles in place. Thanks ;-)
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Old 06-28-2007, 07:41 PM
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Originally Posted by Dark8 View Post
Like I said, "I agree that going a few pounds lighter ...... is kind of a waste of money ....." That's just my opinion. I have no problem with people dumping loads of cash into a car. To each his or her own - it's their money. Improving the looks and performance of one's car is a worthwhile endeavor.

I just hate seeing somebody throw an $800 lightened flywheel in their car and then stick heavy 19" bling wheels on negating the effect of the flywheel. I did the math and for me the added performance and cost savings of the 17" wheel/tire combo made sense. The $280 I save each year on tires will pay for the wheels in three years. And I'm also seeing the performance benefits of the smaller diameter tires and lower unsprung weight.
I didn't realize so many people only installed lightweight flywheels to only decrease the weight of the CAR. I always thought the purpose of a lightweight flywheel was to decrease the inertia of the flywheel and fix delay problems that seem all-too-common for the overly-heavy stock flywheel.
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Old 08-29-2007, 11:58 PM
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Sorry, this is off topic a little, but I couldn't help responding to this:

Originally Posted by SdotConley View Post
***REMEMBER YOUR 8 REPRESENTS WHO U R*** a car is a personality. So whats your personality?
No matter what you do to your car, no matter how much money you spend, someone else can always spend more and find a more talented fabricator to one-up it. Maybe even before you're finished with your vision.

The only thing you can do with and to your car that's totally unique and a reflection of you that nobody else can do exactly the same is drive. Maybe someone else will be better, but how you drive will follow you into any car you're in, unlike the money you spend on mods.
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Old 08-30-2007, 12:56 AM
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Originally Posted by TeamRX8 View Post
Light weight alone is not necessarily a true picture.

Light weight means nothing if the wheel flexs under load, It often happens that a heavier wheel can have a lower inertia than a lighter wheel; SSR wheels are notoriusly light in the hub area where there is little impact on inertia with excess mass in the shell area which has the largest impact on inertia. How the weight is distrubuted across the width i.e. relative to the lever arm working on the shock/spring, also has an impact. So to simply say this wheel weighs less than that one and is better or 1# rotating mass = 1.5# of non-rotating mass is false science.
Yeah, what Team said. I'm not going to say Rob from Robispec knows everything, but he's done a lot more with suspension than I have, and he is adamant that a slightly heavier but stiffer wheel he changed to had given him more consistent suspension setups. He was able to get a car really dialed in, rather than chasing an unpredictable target, making the car ultimately faster.

This was actually the NTO3-M, which in 17x9.5 is able to clear StopTechs, whereas the 18x9.5 RPF-1 can't, due to the dish of its spokes. Not to take anything away from Goodwin. There are some good 275/40-17 tires out there, too. 255/40-17 is a Porsche OE rear size, so basically every serious performance tire in the world comes that size, and it's a really good match for a 9.5-in. wheel. I guess that's a suggestion for track rubber. There are fewer 255/45-18 tires, but that may be a nicer street size to keep the revs down on I-5.

The moment of rotational inertia is what you're concerned with in straight-line acceleration. Every bit of mass contributes by the square of the radius from the axis of rotation to its location. So an 18-in. wheel with the same weight as a 17-in. wheel will still slow you down more. SCC found this when they did a 16-17-18 test because they couldn't think of anything else that was worth doing with their long-term Mitsu Eclipse (gen 3).

Reducing your tire OD by an inch or more takes you out of the discussion, because your observed increase in vehicle responsiveness is likely due significantly to the advantage gained in gearing.

Remember the Sport Compact Car Technical Assistance Program, where they took some poor schmuck's Sentra to the drag strip and turned it into a golf cart? By far the biggest improvement in ET they were able to achieve was going from heavy 19" show wheels to stock 14s with shyte tires off a G20. I still can't decide what part I liked better: where they Sawzalled off the wing or when they had a big galoot jump on the fiberglass rear bumper one time to remove it.

On my BMW, the light weight of the SSRs makes near-race spring rates tolerable on the street. Heavy wheels would make it suck.

I have driven many, many cars with a lot of different wheels. I have homed in on a particular set of crappy characteristics that represent "heavy wheel feel." It's real.

I have also done skidpad tests on another vehicle, where we over-tired a wheel. With 18x10.5 wheels, we tried 295/30-18 and 315/30-18. The tire temperatures were more even with the wider tires, but the lowest one was higher than the highest temperature with the 295s. With the wider tires, the tires were making more noise and the car was going slower. So even beyond saying you should have a wide enough wheel to support the rubber you're using, it may be that using a narrower tire on the wheel you have could actually be better.

My theory on wheels is that their job is to connect the tires you want to use to the vehicle and support them properly, while clearing the brakes you want to use.

Step 1: What brakes do I want to use?
Step 2: What is the smallest diameter wheel that will fit over the brakes?
Step 3: How wide is the widest tire I can fit, and what OD is appropriate?
Step 4: What is the widest wheel I can fit, and what offset range do I need to have it clear the suspension and the tire clear everything?
Step 5: What tires do I want to use that work with 2, 3, and 4? Are they available? Can I afford them?
Step 6: Shop for wheels of the correct diameter, width, and offset, with sufficient clearance for the brakes and decently light weight that I can afford.

So what did I do?
I have a set of 18x10.5 +43 et wheels in the garage waiting for my 8 to get here. Not quite as light as Team's, but close. There aren't many lightweight 17x10 or 10.5 wheels out there that fit the 8, fewer that clear StopTechs (I always try to leave that door open). In fact, the only ones I can name are Volk$.

I also have a set of 17x8.5 SSRs left over from my last project, which will be my street wheels.
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Old 08-30-2007, 01:07 AM
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Originally Posted by Backstyck View Post
I didn't realize so many people only installed lightweight flywheels to only decrease the weight of the CAR. I always thought the purpose of a lightweight flywheel was to decrease the inertia of the flywheel and fix delay problems that seem all-too-common for the overly-heavy stock flywheel.
The reasons you state are good ones, but anything you do to remove mass from a vehicle helps. Other than the money spent, light flywheels are generally low-compromise items.

As far as straight-line acceleration, the benefits are greatest in first gear, diminished in second, diminished still more in third, and basically hard to measure in fourth.

Hannu Prettner (sp?) was a multi-time world champion in R/C airplane aerobatics when I was a kid. His single piece of advice for anyone wanting to build great airplanes? Build with a gram scale. Think about the weight of the plastic film you're covering the plane with, think about how much glue you're using. Buy more wood than you need to, and sort it for lightness.

The point is that small differences often don't by themselves mean much, but the accumulation of many very small differences can yield a real advantage. It's how an Evo gets down to 2200 lb and becomes magic.
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Old 12-03-2007, 03:35 PM
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Broken links make me sad. =(
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Old 01-14-2008, 11:24 PM
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More info?

I agree, but I think there is more of an equation that that; or at least fill in a blank for me:

Rather than undefined rotational mass to some form of power measurement (at a rate between 2.2 and 3)... Pounds of rotational mass to horsepower equation maybe?

An equation like that would be very useful if you or someone has it.

Hope you don't see this as a dick move. I'd really like to know.
Thanks


Originally Posted by crossbow View Post
Weight is power. Ask a drag racer which they'd rather have. Minus 50 lbs, or 5 hp.

Its all about power to weight. Increase your weight, and you have to increase your power to compensate. Increase your rotational mass, and the power increase required to maintain similar power levels increases by a factor of 2.2-3x.

Its all in the orgy of urls...but nobody can force you to look at them.

http://www.nerocam.com/SCC_TAPnew.asp
2.0 seconds off the 1/4, and they didn't increase power at all. :D
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Old 01-20-2008, 01:29 PM
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Originally Posted by Bradleydrivn View Post
Rather than undefined rotational mass to some form of power measurement (at a rate between 2.2 and 3)... Pounds of rotational mass to horsepower equation maybe?

An equation like that would be very useful if you or someone has it.
The basic problem with most of these discussions is they are based on a woefully incomplete application of the simple F=MA. Acceleration is the force available to accelerate the vehicle at the speed it's going (subject, of course, to the limit of traction; also, this is really torque geared to the speed you're going - power is the common expression of this) minus the force of resistance such as aerodynamic drag and rolling resistance, divided by the total of inertial effects (mass to be translated plus rotational inertia of the spinny parts).

The "pounds of rotating mass to non-rotating mass" relationship depends on how much of the inertial effect is accounted for by the rotational inertia, how the pounds of each rotating item are distributed to contribute to rotational inertia, and how much power the car has. It's all percents.

To take this to an extreme, if you had 10 hp, and added 10 hp, the change would be massive. If you had 400 hp and added 10 hp, you may not even be able to isolate the change at the drag strip.

It's still a pretty simple equation. The hard part is knowing what values to put into it to get a real answer. It's impractical for anyone but the OE manufacturer of a vehicle to assemble the data. Extensive road tests can approximate aero and rolling resistance values if analyzed with a good model. Rotational inertia of the complete vehicle pretty much needs a complete vehicle model. If we have a good chassis dyno plot and good data on actual vehicle performance, then predicting the effect of a change in inertia should be within reach.

It should be possible to build a test rig to determine the rotational inertia of things like wheels and brake rotors, but I've never seen anyone do it. The manufacturers of these items will have CAD models and should be able to get a number for rotational inertia with a few clicks, but good luck getting them to tell you what it is.

In the real world, where people care more about making cars go fast than about talking about it, the six-step plan I outlined above is pretty good.

If you do have the resources to test multiple setups accurately (measurement equipment, consistent and fast driver, track time, parts to swap out, etc.), then you can certainly choose between them and even understand the differences. There is a lot more than lap times. If you understand where one setup may give you better braking or cornering, and another may give up some of that but through lower inertia, rolling resistance and drag, give you higher speed on longer straights, you may be able to predict where one setup would be favored over another. More likely, you'll make a choice on parts and invest in it, then work on optimizing the setup of those components at each place you go.

If that seems too hard, then you should probably do what everyone else does (including me and the author of http://www.nerocam.com/SCC_TAPnew.asp), which is look at what fits, pick out the ones that look good to you, weigh your own values of price versus weight, and lay down your dollars. Then go work on optimizing the nut behind the wheel.
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Old 02-20-2008, 02:53 PM
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holy crap all this reading is killing me, i feel like im reading a book about the citric acid digestion process. can any one simply tel me whether or not : a. putting new 18' wheels on stock tires will work and b. does lighter tires and wheels affect acceleration performance ...thank you and no einstein answers please
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Old 02-20-2008, 03:19 PM
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Sure - I'll tell you

- Putting new 18" wheels on stock 18" tires will work.
- YES! Lighter wheels and tires affect accelerative performance.

Bong! That was easy!
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Old 02-20-2008, 03:36 PM
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Well i did a fuel economy experiment.

Basically everytime i did a +1 on diameter and width i lost about 10% of the fuel economy. FYI.

Tested on my RX8 and Miata.

Rishie
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Old 05-29-2008, 03:24 PM
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a lot of the links in the first post are broken
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Old 06-19-2008, 10:31 AM
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Originally Posted by Endless Rotaries View Post
Basically everytime i did a +1 on diameter and width i lost about 10% of the fuel economy. FYI.
Did you account for the fact that your odometer is reading low?
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Old 02-06-2009, 03:05 PM
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Anyone know what the OEM Chrome wheels weigh on a 2004?
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Old 07-11-2009, 07:58 AM
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I have Gramlites-18x8.5. Does anyone happen to know how much they weigh??
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