Articles
Size Matters
http://www.wam.umd.edu/~greghess/sizematters.pdf
Finding Free Power
SCC Technical Assistance Program
Bicycles and Unsprung Weight
http://www.softride.com/bike/cornering.pdf
Fixing the 350Z: Why Lawyers Want Everyone to Run Staggered Setups
Project Nissan 350Z Part 2 - Project Cars - Sport Compact Car Magazine
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
Wheel Tech - Road Wheel Weights Can Affect Your Vehicle's Show...and Go
The Danger of Dubs
http://www.edmunds.com/insideline/do/Featu...rticleId=104526
Automobile Ride, Handling, and Suspension Design
Automobile Ride, Handling, and Suspension
Threads
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.
Full Version: Effects of Wheel Size/Weight on Performance
Mazda6 / Atenza > Technical / Performance / Model > Mazda6 1st Generation (2002-2008) > Wheels / Tires
awesome, just awesome!
wow.
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.
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.
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.
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.
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.
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.
Now THAT was an entertaining AND educational lesson
2 Testts, 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
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
What's the weight of the stock wheels?
Nevermind. I found it.
Nevermind. I found it.
QUOTE(JettaJet @ Mar 10 2005, 03:14 AM)
What's the weight of the stock wheels?
[right][snapback]375398[/snapback][/right]
[right][snapback]375398[/snapback][/right]
21.5 lbs
Wow, lots of info!
Previously pinned topic. Please re-pin.
QUOTE(6ownzU @ Mar 10 2005, 12:29 AM) [snapback]375407[/snapback]
21.5 lbs
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..
Stock 17s weigh 21.5 lbs.
QUOTE(davecoyne @ Jul 6 2006, 03:01 PM) [snapback]726657[/snapback]
Stock 17s weigh 21.5 lbs.
Found its 21.1 lbs for the 16's... thanks.. guys..
QUOTE
Does anyone know of any 18's that weigh less than 16's?
To counter out the effect of the increased diameter, they'd have to be nearly 8-10 lbs lighter then the 16's they are replacing.
Smart
QUOTE(ReCLaIM @ Jul 7 2006, 02:10 AM) [snapback]726666[/snapback]
Found its 21.1 lbs for the 16's... thanks.. guys..
Stock 17s weigh 21.5 lbs.
Stock 17s weigh 21.5 lbs.
u mean the 17s and the 16's have quite similiar weight?
can mod fix the miata.net links....all of them are broken!
thx!
thx!
QUOTE(kenairs @ Jun 2 2007, 10:31 AM) 
u mean the 17s and the 16's have quite similiar weight?
I bought used stock 16's, weighed 23.0 lbs each .... sold them.
oem 16" off mazda3 are 16 x 6.5", 17 lbs ea.
Just to let peeps know. I just updated and cleaned up all of those links. If you see any more dead ones, send me a pm. I was spreading around some love on the 3 forums, so figured I should update it here as well. Also added a few new ones...shame on the 6tech ones, that forum is difficult to search now. 
Thank you for doing this, Crossbow! Mad props!
lots of good links, but how about some bottom line results: Audiworld had a good derivation: http://www.audiworld.com/tech/wheel13.shtml
Assume you have oem 17"rim/215 tires at about 44 lbs each. You find new tire/rim set of 4 with exact same rolling radius, but 10 lbs lighter. They have less static weight, and less rotating weight.
AT BEST, if all the weight loss was using magic foam rubber at the tire OD, then per corner, you save 10 lbs static weight and 10 lbs rotating weight (with an implied factor of static + inertia of 2.0). This means, assuming same road interface efficency, new setup will run as if you dropped 20 lbs off each corner, or 80 lbs off the total car weight (including wheels) for a set of tires/wheels that is 40 lbs lighter.
The 2.0 inertia factor is an extreme limit. A more accurate average factor is 1.7 or so. So dropping 10 lbs at tire/wheel per corner has a net effect of dropping 17 lbs per corner, including inertia effect..
Assume you have oem 17"rim/215 tires at about 44 lbs each. You find new tire/rim set of 4 with exact same rolling radius, but 10 lbs lighter. They have less static weight, and less rotating weight.
AT BEST, if all the weight loss was using magic foam rubber at the tire OD, then per corner, you save 10 lbs static weight and 10 lbs rotating weight (with an implied factor of static + inertia of 2.0). This means, assuming same road interface efficency, new setup will run as if you dropped 20 lbs off each corner, or 80 lbs off the total car weight (including wheels) for a set of tires/wheels that is 40 lbs lighter.
The 2.0 inertia factor is an extreme limit. A more accurate average factor is 1.7 or so. So dropping 10 lbs at tire/wheel per corner has a net effect of dropping 17 lbs per corner, including inertia effect..
this was a really good writeup on the mechanics/physics...
The effects of wheel weights will be different depending upon the type of driving. For skidpad and racetrack performance, you won't notice too much of a difference between light & heavy wheels. But try some canyon carving up Mulholland (Malibu) or Old San Marcos (S.B.) and you will definitely see an obvious difference. Wheels & tires are unsprung weight, meaning they aren't controlled by the suspension and will follow the contours of the road.
When you hit a 6" bump, that wheel & tire will move up 6". The energy this imparts through the suspension into the body will depend upon the mass of the wheels & tires. A 55-lb combo will hit the body harder and launch it off the bump more than a 40-lb wheel & tire. The more energy pushing up on the body, the higher it will move the body and the more the body will pull on the suspension as it launches off the back side of the bump, lossing traction momentarily.
Similar thing when you drive over a drop. Gravity will pull the wheel down with a fixed force. The springs then pushes down another amount based upon the spring rate. A heavier wheel & tire will get pushed down slower with the same spring-rate. Thus there's more 'hang' time over the bump, meaning you have wait longer to regain traction. This longer drop time also causes the body of the car to fall more into the hole than with a ligher wheel. Dropping more into the hole also means a bigger launch coming out of it.
So overall, on bumpy terrain, light wheels & tires allow the suspension to keep the body more level with a constant load on all the tires for best grip. Heavier wheels & tires tend to make the body bounce around more over the same terrain and this jostling causes uneven load on the tires and gives less grip.
The unsprung weigh of the rear axle comes into play here as well. Take a rough, bumpy mountain road all out with a solid rear axle. Then try it again at the same speed with an IRS rear end and you'll notice a dramatic improvement in cornering and drive traction.
The effects of wheel weights will be different depending upon the type of driving. For skidpad and racetrack performance, you won't notice too much of a difference between light & heavy wheels. But try some canyon carving up Mulholland (Malibu) or Old San Marcos (S.B.) and you will definitely see an obvious difference. Wheels & tires are unsprung weight, meaning they aren't controlled by the suspension and will follow the contours of the road.
When you hit a 6" bump, that wheel & tire will move up 6". The energy this imparts through the suspension into the body will depend upon the mass of the wheels & tires. A 55-lb combo will hit the body harder and launch it off the bump more than a 40-lb wheel & tire. The more energy pushing up on the body, the higher it will move the body and the more the body will pull on the suspension as it launches off the back side of the bump, lossing traction momentarily.
Similar thing when you drive over a drop. Gravity will pull the wheel down with a fixed force. The springs then pushes down another amount based upon the spring rate. A heavier wheel & tire will get pushed down slower with the same spring-rate. Thus there's more 'hang' time over the bump, meaning you have wait longer to regain traction. This longer drop time also causes the body of the car to fall more into the hole than with a ligher wheel. Dropping more into the hole also means a bigger launch coming out of it.
So overall, on bumpy terrain, light wheels & tires allow the suspension to keep the body more level with a constant load on all the tires for best grip. Heavier wheels & tires tend to make the body bounce around more over the same terrain and this jostling causes uneven load on the tires and gives less grip.
The unsprung weigh of the rear axle comes into play here as well. Take a rough, bumpy mountain road all out with a solid rear axle. Then try it again at the same speed with an IRS rear end and you'll notice a dramatic improvement in cornering and drive traction.
QUOTE (Toadster @ Aug 26 2008, 02:50 AM)
this was a really good writeup on the mechanics/physics...
.... So overall, on bumpy terrain, light wheels & tires allow the suspension to keep the body more level with a constant load on all the tires for best grip. Heavier wheels & tires tend to make the body bounce around more over the same terrain and this jostling causes uneven load on the tires and gives less grip.
The unsprung weigh of the rear axle comes into play here as well. Take a rough, bumpy mountain road all out with a solid rear axle. Then try it again at the same speed with an IRS rear end and you'll notice a dramatic improvement in cornering and drive traction.
.... So overall, on bumpy terrain, light wheels & tires allow the suspension to keep the body more level with a constant load on all the tires for best grip. Heavier wheels & tires tend to make the body bounce around more over the same terrain and this jostling causes uneven load on the tires and gives less grip.
The unsprung weigh of the rear axle comes into play here as well. Take a rough, bumpy mountain road all out with a solid rear axle. Then try it again at the same speed with an IRS rear end and you'll notice a dramatic improvement in cornering and drive traction.
Yup. Main benefit of light wheels and tires is handling and smooth ride, not 0-60 times.
QUOTE (Hoosteen @ Feb 5 2005, 05:29 PM)
Now THAT was an entertaining AND educational lesson
it doesnt even have a gascap for saving that extra .0000007 lbs!
btw anyone know if I can still go up in wheelsize after installing springs?
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