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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
SCCAForums.com - How much will 17" wheels slow you down

Effect of Lighter Wheels?
SCCAForums.com - Affect of lighter wheels

Bigger Wheels and Tires?
SCCAForums.com - Bigger wheels and tires?

Rotational Advice
MX-5 Miata Forum - Rotational weight advice please

If larger wheels are bad...why do sports cars have them?...
MX-5 Miata Forum - If larger wheels are so bad, why does every sports car in the world have them?

Increased Wheel Weight? Significantly Slower?
MX-5 Miata Forum - increased wheel weight = significantly slower?

The Real Effect of Additional Wheel Weight!
MX-5 Miata Forum - The REAL effect of additional wheel weight!

Wheel Weights....Can They Make a Difference?
MX-5 Miata Forum - Wheel weights...can they make a difference?

33.5 lbs/Corner Too Heavy??
MX-5 Miata Forum - Whadda think? 33.5 lbs/corner too heavy?

Wheel Weight Reduction for Bloated Cars
MX-5 Miata Forum - Weight reduction for our bloated cars?

Don't Small Wheels Mean Heavier Tires?
MX-5 Miata Forum - Don't small wheels mean heavier tires?

Whats With Huge Wheels?
MX-5 Miata Forum - What's with huge wheels

18" Wheels too big? Take a Look!
MX-5 Miata Forum - 18" Wheels too big? take a look

I'm Finally Completely Convinced About Lighter Wheels and Tires
MX-5 Miata Forum - I'm finally completely convinced about lighter wheels and tires

Do Wider Tires REALLY Provide More Traction?
MX-5 Miata Forum - Do wider tires REALLY provide more traction?

Unsprung Weight 101
MX-5 Miata Forum - Unsprung Weight 101?

Losing 4 lbs per wheel. Will I notice it?
MX-5 Miata Forum - Losing @4lbs per wheel, will I notice anything?

Unsprung Weight? Is the difference substaintal?
MX-5 Miata Forum - Unsprung weight increase - is difference significant or negligible.....really!

WO! The Joy of Lightweight Wheels!!!!
MX-5 Miata Forum - WO! THE JOY OF 6.5 lbs. WHEELS!!!

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!!!
Spreadsheet blows lid off lightweight wheel debate!!! - MINI2 - MINI Forum

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/viewtopic.php?t=1762&start=0

17 vs 18 Wheels on the Mazda 6 @ the Track
Stock 17's Vs aftermarket 18's...1/4 mile time - Mazda6 / Atenza

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

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

Some Wheel Weight Sites
WHEELWEIGHTS.NET
Wheelspecs.com :: Free wheel database :: street, racing, and off-road wheels & rims :: specs, weights, photos
Miata Garage Tires and Wheels

I will continue to update these links as more are found or added.
 

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COUNTERPOINT

Plus sizing is not a bad thing. There are many benefits to plus sizing including improved handling and braking. Some of the articles above refer to SUV/truck plus sizing as being dangerous, and here's why (this wasn't mentioned): Many of these 20-24" upgrades can be adding as much as 35 lbs. of unsprung weight to each corner! The factory brakes/shocks/springs are simply not designed to accomodate this much extra unsprung weight.

Most upgrades to the Mazda 6, including many 19 inch fitments would not qualify as dangerous, unless you are fitting tires that do not meet the load requirement of the vehicle. Simply be aware of the total weight of the wheel/tire package. You have no control over where the weight is distributed in the wheel/tire package and simply by nature of the design, it tends to be more outward (polar moment of inertia). Many low profile tires can overcome this.

During my days at Yokohama, the method of "Inch Up" was thoroughly researched and tested. The benefits were proven. Here is an example: (Note: this information is taken from Yokohama's 2004 Fitment Guide and has been in use since at least 1999. The sizes below do not match the sizes for a 1989 Mazda RX-7. The only explanation I have is that the lap times and lateral forces were taken from another vehicle, but the RX-7 was mistakenly listed as the test vehicle. This in no way invalidates the results [the sizes are consistent with a 1997 Ford Thunderbird].)

"An independent research company recently conducted a test to determine the effect Inch Up has on handling. Included here is an abbreviated summary of the test results.

The vehicle used for this comparison was a 1989 Mazda RX-7 SE. The original equipment tire is a 185/70HR14, and is mounted on a 5.5-inch wide wheel. The test was conducted on a dry asphalt surface.

As the results from the lateral acceleration and handling course indicate, each successive plus size led to a noticeable increase in handling performance.

FITMENT - TIRE SIZE - (% OF ORIG) - RIM SIZE - LAT G - LAP TIME

ORIG EQUIP - 205/70R15 - 100% - 6" x 15" - 0.763 - 32.320
PLUS ZERO - 205/65R15 - 99% - 6" x 15" - 0.836 - 31.239
PLUS ONE - 225/60R16 - 101% - 7" x 16" - 0.850 - 30.587
PLUS TWO - 255/45R17 - 99% - 8.5" x 17" - 0.934 - 29.213

(end of quoted article)"

As with any modification, there is a point of diminishing returns. Upgrades to 18, 19, 20-inch and above may or may not produce improved results. This is dependent on many factors, not the least of which is weight of the wheel/tire package. A 16-inch factory alloy wheel may outperform a heavier 18-inch cast aluminum wheel. However, a forged aluminum 18-inch wheel may handily outperform a heavier 16 or 17 inch cast aluminum wheel. It depends on the vehicle, spring and shock rates, weight of the tire and, of course, the tread design and compounding of the tire as well.

It is very difficult to make blanket statements regarding plus fitments. There are so many variables, you would have to test all of the wheels and tires on the market in the various combinations and permutations on your specific vehicle to determine the differences. What may work on an Audi A4 or Nissan Altima may not produce the same desired results on a Mazda 6. And if you came back to the track the next day for more testing and the conditions were different, you might get different results.

You must first determine what is most important to you. Are you simply looking for improved performance on the street? This can most often (and most inexpensively) be achieved by upgrading to better tires. However, the lower profile and stiffer sidewall of plus sizing your wheels will often result in even greater transient response and shorter braking distances, even with a moderate increase in unsprung weight.

If you are looking for improved track performance, than ultra light weight wheels and tires with the stickiest compounds will be the ticket for you. The trade off being the reduced tread life and potentially higher instance of broken or bent wheels. Also consider that what works on an autocross course may not produce the same desired results on a high speed road course.

If great looks and big wheels (such as 19s) are your thing, be prepared for potentially reduced performance, ride quality and fuel mileage. Every modification requires some sort of compromise. Inform yourself before making your purchase decision, decide which compromises you are willing to live with and you will be happier with the results.
 

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Discussion Starter #5
Toyoguy,

The first article posted...
http://www.wam.umd.edu/~greghess/sizematters.pdf

Has completely different results from what you just posted. The 15's are faster then the 16's, and the 17's are slower then the 16's, even though the 17's have the lowest profile tires. Does show diminishing returns though, as the 15's are not signficantly faster then the 16's, but the 16's are considerably faster then the 17's.

They even used the same tires (Toyo T1-S), and only adjusted the sidewall height between trials.

Perhaps the differences between the two studies were that yours has the highest profile of 70, while in the above study, the difference is 50 profile (on 15's), 45 on 16's, and 40 on 17's...much closer together. Additionally in the above study rim and sidewall widths were just changed...just diameter and sidewall heights.

I'd like to see your study where rim width stayed the same. I'm almost positive the 16's would have beaten the 17's then. 1.5 inches of additional rim width is a pretty major advantage in sidewall stability. Kinda of skews the final results =/. It is however an excellent example of how wider/lower profile tires are superior to high profile thin ones.
 

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ToyoGuy, your test went from a 205 wide tire to a 255 tire on a allegedly heavy car (a Thunderbird). No wonder you got those results! Want to bet that a 255/50/15 (if such a tire existed) would be a heck of a lot faster than a 205/50/17?

It wasn't a fair comparison! And the test only went to a 45 profile, which is hardly an agressive profile by today's standards. That's the starting point on the Mazda6!

I contend that will handle better than 225/45/17 on a 17x7" wheel which will handle much better than a 225/40/18 on a 18x7" wheel which will handle much better than 225/35/19 on any size wheel.

The test Crossbow posted kept tire widths the same, but the wheels got skinnier- still not a fair comparison, but it was enough to show the drawbacks of big wheels.
 

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2 Tests, Apples and Oranges .....

First test was on a road course, with limited power VW. Usually it's easy to get too much contact width in that case. The lower the aspec ratio, the wider the contact width, in most cases. Also, deeper tire section will help act as suspension in bumpy corners. Results might have been different if 200 more hp was involved.

2nd test was on an asphault "handling circuit" sounds like auto-x. As a rule in auto-x, the wider the tire the better. Lateral g's is critical.

Autox always tore up my tires more that road circuit events. just my $.02
 

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21.5 lbs
[/b]
Is this the weight of the stock 17's? or 16's?

Does anyone know of any 18's that weigh less than 16's? I tried to read through all of these articles.. and holy hell.. lol..
 

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Stock 17s weigh 21.5 lbs.
[/b]
Found its 21.1 lbs for the 16's... thanks.. guys..
 
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