anyone know the benifits of lightweight wheels?

[BrazdonW]

i understand lighter wheels should be less work for the car and maybe pep the car up some but im wondering by how much? is there some kind of formula i can use to determine it?

[BrazdonW]

sorry wrong thread
but i still need answers lol

[eTiMaGo]

I'm not sure of an actual formula, but search google for the following terms:

Unsprung weight
rotational inertia

and you'll learn a lot :wink:

[BrazdonW]

good plan :)

[slvryaris]

Just less total weight. I seen something once talking about gas mileage for every like 100lbs you loose off your car you gain like 3% more fuel effiency. I have seen people toss their spare tire and everything.

[CaysE]

Just less total weight. I seen something once talking about gas mileage for every like 100lbs you loose off your car you gain like 3% more fuel effiency. I have seen people toss their spare tire and everything.

Less rotational weight has a larger effect than less total weight. It's the same thing as having a lightweight flywheel: your engine can rev faster because there's less resistance to it spinning. It doesn't increase horsepower or torque (except to the ground), but it does increase acceleration.

[kimona]

I find it hard to believe that reducing rotational weight by just a few pounds per corner will make any significant difference in fuel savings or acceleration.

[CaysE]

Welcome to physics 101. o.O

And "significant" is subjective. On a car that makes less than 100hp, dropping 5 pounds off of each wheel is going to make difference enough that you'll notice it.

[Turbo&Auto]

True story.

[brickhardmeat]

unsprung weight matters, the less the better:thumbsup:

[CaysE]

Lower unsprung weight is a result of lightweight wheels, as well, and will improve suspension response.

[kimona]

Welcome to physics 101. o.O

And "significant" is subjective. On a car that makes less than 100hp, dropping 5 pounds off of each wheel is going to make difference enough that you'll notice it.

Actually "significance" is not subjective; it is a mathematical calculation with a foundation in simple statistical analysis.

Certainly less rotational weight makes some difference... "Welcome to physiscs 101"... but the question is whether a few pounds per corner will make any significant difference in gas consumption and acceleration.

[brickhardmeat]

Actually "significance" is not subjective; it is a mathematical calculation with a foundation in simple statistical analysis.

Certainly less rotational weight makes some difference... "Welcome to physiscs 101"... but the question is whether a few pounds per corner will make any significant difference in gas consumption and acceleration.

the difference in consumption will likely come from over all weight loss any loss woul be a benefit to a degree but the unsprung weight is the wheels and tires

I think I'm just agreeing with you here

[kurokoma-kun]

My question would be, is there any disadvantage to lightweight wheels?

I bought mine based on design, but was pleased to find out they weigh just 11.8 lbs apiece! Then I read something that said wheels can be too light...something about reduced traction...which just confused the hell out of me...

[brickhardmeat]

My question would be, is there any disadvantage to lightweight wheels?

I bought mine based on design, but was pleased to find out they weigh just 11.8 lbs apiece! Then I read something that said wheels can be too light...something about reduced traction...which just confused the hell out of me...


I doubt anything we could get are hands on in a 14 inch or more wheel size would be too light with a tire on it. I've never heard it put that way. I have heard about braking problems with oversized wheels. I think the lighter the better but then strength maybe an issue

[CaysE]

Actually "significance" is not subjective; it is a mathematical calculation with a foundation in simple statistical analysis.

Certainly less rotational weight makes some difference... "Welcome to physiscs 101"... but the question is whether a few pounds per corner will make any significant difference in gas consumption and acceleration.:confused:

If you drive the car to work a few times a week and have plenty of money for gas, it is far less significant than someone else who is on a road or auto-x course looking to shave off tenths of a second. This is called subjective. English 101?

I'm just busting your balls, don't take it personally; I don't even know you. :respekt: :drinking: I think we're on the same page... you're talking about daily driving and I'm talking about racing. You're not going to notice like a 20% improvement in gas mileage or something crazy, but you'll definitely notice better course times.

:biggrin:

[WRBlue]

I think the lighter the better but then strength maybe an issue

Thats the only issue for lightweight wheels.

If you ever look at Kodiak wheels, they are made for racing only. They aren't built to withstand the rigours of daily driving with pot holes and road debris. Driving with race wheels on the street is asking for a cracked wheel... But we're talking about <10lb 14" wheels...

[kurokoma-kun]

Ok so...

less rotating mass = reduced inertia = faster accel/deceleration?
lower unsprung weight = less up-down+side-to-side motion = better grip?

[keesue]

Ok so...

less rotating mass = reduced inertia = faster accel/deceleration?
lower unsprung weight = less up-down+side-to-side motion = better grip?


Faster suspension response (up and down) due to less weight. The shocks don't have to absorb the heavier mass; and, faster steering respone for the same reason. "Quick" is the word when lighter wheels are installed, as in, "dayum, dis steerin' sho is smooooth' (spoken in inner-city ebonics for emphasis). :thumbup: And....the lower the profile tire, the greater the risk of damage. Typically, its best to use a 15" wheel with a 60 series tire to absorb the punishment of road hazzards. You get super quickness and ride quality at a slight penalty in handling. I'm going 15's...

[cleong]

I find it hard to believe that reducing rotational weight by just a few pounds per corner will make any significant difference in fuel savings or acceleration.

Unsprung weight is bad for handling. Unsprung rotational weight is worse. The bit less wheel weight makes your car accelerate and brake faster.

You see some racing cars run bigger wheels simply because they need to fit bigger brakes inside the wheels, for lower stiffer sidewalls, and because they have power to spare to turn monster 18 inch wheels.

Which is why I can't see the point of anything bigger than 16s on a Yaris. The car isn't fast as stock, you're making it slower by throwing wagon wheels on it.

[keesue]

Unsprung weight is bad for handling. Unsprung rotational weight is worse. The bit less wheel weight makes your car accelerate and brake faster.

You see some racing cars run bigger wheels simply because they need to fit bigger brakes inside the wheels, for lower stiffer sidewalls, and because they power to spare to turn monster 18 inch wheels.

Which is why I can't see the point of anything bigger than 16s on a Yaris. The car isn't fast as stock, you're making it slower by throwing wagon wheels on it.

Well said.:clap:

[jmew0ng]

the real question is how much do the steelies weigh so we can have something to compare xD (without tires)

[fu_im_from_texas]

I've been thinking about this question for a few days. My gut reaction was: lighter wheels will make a significant improvement in accelleration and mpg. My calculations show the opposite. Maybe my logic is flawed? Here's what I've got so far.

Consider two cases:
1) Totally stock Yaris from 0-60mph
2) Yaris with lightweight rims from 0-60mph (NOTE: I'm assuming identical tires)

The easiest way to compare the two is from an energy standpoint.

Rotational Energy of a Wheel = .5*Mw*(Rw^2)*W^2

where:

Mw= Mass of the wheel
Rw= radius of the wheel
W= rotational speed (Radians/second)

For Case 1)
Mw= 15lbs. I base this on the wheel/tire combo weight of 33 lbs. tirerack.com says the tire weights 18lbs. 33-18=15
Rw = 7.5 inches. 15in diameter / 2
W = 92.15 (RAD/s). @ 60mph 1mile takes 60 sec. for stock tires tirerack.com says 880 rev/mile so 880/60 = 14.6Rev/second *2Pi= Rad/s

convert to metric

Mw= 6.8kg
Rw=.19m

Rotational Energy = .5*Mw*(Rw^2)*W^2 = .5*6.8*(.19^2)*92.15^2
=1042 watts = 1kWatt

For Case2)
Mw=10 lbs. = 4.5kg This seems like a reasonable lightweight 15 inch wheel
Rw=7.5 inches = .19m
W = 92.15 RAD/s

Rotational Energy = .5*Mw*(Rw^2)*W^2 = .5*4.5*(.19^2)*92.15^2
= 690 watts = .69 kWatt

1- (690/1042) = 33% less energy to accellerate the lighter wheel. This sounds like a lot untill you compare it with the total energy of the car @ 60mph.

Energy of Yaris = .5*M*(v^2)

Where:
M=mass of yaris=2200 lbs = 998kg
v=velocity=60 mph= 97 km/h

Energy of Yaris = .5*998*(97^2) = 4695 kWatts

so (Energy of Wheel) / (Energy of Yaris) @ 60mph is 1/4695 = .0002

.000002% of the total energy is insignificant.

Did I make a stupid error in my calc? :iono: i would have guessed lightweight wheels would make a big difference...but I proved the opposite. someone help? ...show me the error...

[cleong]

I couldn't really understand the calculations you have done, and I am not a physics major, but would that be an instantaneous value (0.000002%) requiring multiplication by time factor?

[CaysE]

fu, the weights of the wheels themselves could've told you the same thing without going through all that calculation. 10 lb wheels are 33% lighter than 15lb wheels, thus requiring 33% less energy to move them.

The second half of your equation is only comparing the total weight differences of the car with the two different wheels. The two front wheels are attached to the engine, so you'd also eventually conclude that you have more power to the ground due to less total weight of the moving drivetrain.

Cliffs notes: you're only looking at half the picture.

[Biggie™]

Did I make a stupid error in my calc?

Yep!

You are comparing the amount of energy while driving at 60 mph, not the amount of energy it took to actually accelerate the extra 20 pounds of wheels.

Also you didn't factor the rotational weight effects. You just treated the wheels as a non independent part of a mass that is the car.

[fu_im_from_texas]

...fu, the weights of the wheels themselves could've told you the same thing without going through all that calculation. 10 lb wheels are 33% lighter than 15lb wheels, thus requiring 33% less energy to move them....


CaysE, You are right!...This is only true for the simplest case, which I examined here. If we concidered the case of 17inch 10lb rims, then the moment of inerti would be larger...the moment of inerta grows exponentialy with the radius of the rim.



Cliffs notes: you're only looking at half the picture.

Can you please provide a calculation for the other half of the picture?

...You are comparing the amount of energy while driving at 60 mph, not the amount of energy it took to actually accelerate the extra 20 pounds of wheels...

Biggie, This is false. When the car is going 0mph the energy is 0. When the car is going 60mph the energy is about 4xxx kW. The difference, or amount of energy it takes to accellerate the mass is 4xxx-0 = 4xxx kW

...
Also you didn't factor the rotational weight effects. You just treated the wheels as a non independent part of a mass that is the car....

The first portion of my calculation was the rotational effects...

One error I do see is I compaired the energy of 1 wheel, when there are 4 on a car....multipling the energy of 1 wheel x 4 still nets a neglegable ammount of energy...

Can anyone provide an alternate calculation?

[fu_im_from_texas]

I couldn't really understand the calculations you have done, and I am not a physics major, but would that be an instantaneous value (0.000002%) requiring multiplication by time factor?

cleong,
The time factor would come into account if we were looking for the power required to accellerate to 60mph. Energy/time = power.

I simplified the problem by only concidering the energy required. I believe this is a valid way to model this situation...but there may be an error in my calc...:iono:

[fu_im_from_texas]

...
so (Energy of Wheel) / (Energy of Yaris) @ 60mph is 1/4695 = .0002

.000002% of the total energy is insignificant.

...show me the error...

Woops, I moved the decimal point the wrong way...it should be .002%...which is still far less than 1%... anyone else see mathmatical errors?

[dallas]

Removing weight helps acceleration as it takes less energy to move the mass but beware of diameter too. If you go with a 17 wheel even if its lighter than the stock steel wheel (not many wheels like that) you have moved the mass 3inches further out from the hub (based on 14 wheels) so it will take more enery to turn the wheel. I have 205 50 15 tires on light weight 11lb wheels , the stock steel wheel and tire are still lighter.

[CaysE]

I can't calculate the other half of the picture, because it's more complicated.... dependant on what gear your in, gear ratios, the power output of the motor, and the weight of the moving parts of the drivetrain.

You can roughly determine the increase in HP to the ground by guessing the percentage of weight that is taken away from the total weight of the moving drivetrain with two lighter weight wheels, and comparing this to given HP numbers from the flywheel and the ground.

Like I said, you only have half the picture, which is that there's a .08% decrease in the required energy to move the car. The other half is that you have more power available to output 4695 kWatts faster. The percentage decrease in the required energy to move the drivetrain is much larger than .08%.

[CaysE]

Removing weight helps acceleration as it takes less energy to move the mass but beware of diameter too. If you go with a 17 wheel even if its lighter than the stock steel wheel (not many wheels like that) you have moved the mass 3inches further out from the hub (based on 14 wheels) so it will take more enery to turn the wheel. I have 205 50 15 tires on light weight 11lb wheels , the stock steel wheel and tire are still lighter.

This is not necessarily true, because you're not taking the tires into account. Tires can typically weigh between 15 and 20 lbs, and if you maintain the overall diameter of the wheel/tire combo, a lighter weight wheel with a larger diameter would require a tire with a shorter sidewall, thus a lighter tire. Depending on the actual weights and wheel design, the mass can even be moved inward.

[fu_im_from_texas]

I can't calculate the other half of the picture, because it's more complicated.... dependant on what gear your in, gear ratios, the power output of the motor, and the weight of the moving parts of the drivetrain.

...

We are assuming that gear ratios, power output, and drivetrain weight are all constants...the only change is the wheel weight...

please provide a calculation for the other half...

[CaysE]

I CAN'T provide a calculation. I have no idea what the weight of the drivetrain is, the given flywheel HP and BHP numbers are, or the gear ratios. You need to take into account what gear you're in and the ratio, because the number will be different for every gear. I can go 60mph in 2nd gear or 6th gear in my car... the difference in power output is significant.

If you get those numbers, feel free to calculate it yourself. I find it hard to see a reason for these calculations aside from getting empirical evidence to back up the fact that lightweight wheels do improve braking performance, suspension response, and acceleration. You don't need these numbers to understand what's going on.

[Biggie™]

Biggie, This is false. When the car is going 0mph the energy is 0. When the car is going 60mph the energy is about 4xxx kW. The difference, or amount of energy it takes to accellerate the mass is 4xxx-0 = 4xxx kW

Wrong again buddy... In your equitation you are attempting to calculate the actual energy the Yaris possesses at 60 mph. Not the energy it took to get the car to 60mph. But thank you for letting us know what the ballistic energy of an object that is close to the mass of yaris being flung out at 60 mph.

What you need to do is calculate "force", mass multiplied by acceleration. And of course it will take less energy to accelerate a lighter object. The formula to calculate rotational acceleration is a bit more complex, but this is actually what you are looking for here. Try google...

[eTiMaGo]

Man, I need to find my old physics textbooks :biggrin:

Back on the original topic, I find it easier to explain these phenomena with basic everyday examples...

Effect of total car weight

Imagine you're at the supermarket. How much easier is it to push the trolley around when it is empty compared to when it is full? It's a lot easier to speed up, stop, and turn when you have less weight.

Effect of wheel weight (or pulley, or any rotating mass)

Imagine you have two tops (spinning tops, what kids used to play with long ago...), a heavy one and a lighter one. Think of how much extra twisting force you have to give the heavy one to get it to spin at the same speed as the lighter one. It will also keep spinning longer, and if you try to stop it by hand, you will need more stength to do so.

Also, imagine you are riding a bicycle, and you want to go up a low curb or something similar. You'd usually slow down, because when you go fast, the inertia of the wheel (the same force that lets your bike stay upright instead of falling over, when you are moving), will want to drive the bike straight through the curb, instead of up and over it. In car terms, the lighter the wheel, the less inertia it has, and the easier the suspension can react to bumps at higher speeds.

In reality there is always a compromise somewhere... smaller lighter wheels will help with response, but that means running a taller sidewall which can flex and make the handling less precise.

Also, something I've been pondering, the Yaris is quite tall and kinda top-heavy, so heavier wheels may be an advantage in stabilizing the car, shifting the center of gravity down a bit, keeping the car a bit more planted at speed? This would only be really useful on a highway, but just something that might be worth to consider.

Anyway, I hope that helped, for the less technically-minded out there :wink:

[cleong]

I did some Googlesearching and came out more or less with the ratio of 1:4 (ie 1lb rim weight lost is as good as 4lbs static weight).

It is a best-fit rule of thumb that some people use to simplify the performance advantage of lighter cars.

[kurokoma-kun]

I find it easier to explain these phenomena with basic everyday examples...Anyway, I hope that helped, for the less technically-minded out there :wink:

eTiMaGo, you are my hero :wub: Your point about the weight balance is, I think, what I was asking about originally. Lowering the center of gravity is next step for me.

I don't mind admitting that once you start getting into differential equations and so forth I am completely lost. This is why I was not able to pursue a career in science, because at some point, interactions get so complex they can only be explained mathematically, and I have no intuitive understanding of it. :confused: :rolleyes:

[elsteverino889]

According to http://www.wheelweights.net/ our stock wheels are 16.0 lbs which isnt bad already lets say u get 11 lb wheels thats 20lbs your saving isnt gonna make a tremendous diff but im sure ull get a little more zip out of our little engines

[fu_im_from_texas]

...What you need to do is calculate "force", mass multiplied...

Biggie,
I am approaching the problem from an energy stand point. I base this approach on the first law of thermodynamics - a law that states there is a conservation of energy.

You are approching the problem from the standpoint of Force. You are useing Newtons second law of motion. F=ma...

Both are valid. There is 300+ years of emperical evidence that shows that conservation of energy, and F=ma will ultimately get you to the same answer. I am using conservation of energy because, in this case, it is the simpler approach...



... Try google...

I have a degree in mechanical engineering from the university of texas @ austin. I have taken several classes in physics, dynamics, and dynamic system controlls. My approach to the problem is correct. Google will give you a ton of information. Information is dangerous when it is applied incorrectly...

I am not trying to give you a hard time here, because we are all trying to figure out the same answer to the same tough problem ...

[fu_im_from_texas]

I did some Googlesearching and came out more or less with the ratio of 1:4 (ie 1lb rim weight lost is as good as 4lbs static weight).

It is a best-fit rule of thumb that some people use to simplify the performance advantage of lighter cars.

I've heard "old timers" make a similar claim...only the ratio was 1:7 ... :iono:

[dallas]

I did consider the tires in my weight, and yes the shorter sidewall helps, but the mass of a wheels weight is not in the spokes so if you move it 3" further from the hub even thought the tire tread is the same diameter away as the 14wheel, you have added more mass further from the hub over a stock 14" wheel. I have yet to find a 17" wheel tire combo that I can afford that would weight less than the stock 14 wheel and tire combo.

This is not necessarily true, because you're not taking the tires into account. Tires can typically weigh between 15 and 20 lbs, and if you maintain the overall diameter of the wheel/tire combo, a lighter weight wheel with a larger diameter would require a tire with a shorter sidewall, thus a lighter tire. Depending on the actual weights and wheel design, the mass can even be moved inward.

[cleong]

I've heard "old timers" make a similar claim...only the ratio was 1:7 ... :iono:

There is a range of claims but 1:4 sounds a little less optimistic than a 1:7 ratio. My scanning of other internet forums suggests 1:4 is more commonly accepted.

[fu_im_from_texas]

There is a range of claims but 1:4 sounds a little less optimistic than a 1:7 ratio. My scanning of other internet forums suggests 1:4 is more commonly accepted.

Then maybe my calculation of less than 1% is correct? If the stock wheel weight is 15-16lb and you went with a 10-11lb, then you would save ~5lbs per wheel, or 20lbs total. 20x4=80lbs... imagine a race between two stock Yari...the only difference being, one the driver weights 120lbs, the other 200lbs ... sounds like a dead heat to me?

[CaysE]

I can't tell if you're being sarcastic or not, so based solely on the fact that you haven't been sarcastic in this thread yet, I'll guess that you seem to think both of those cars in your theoretical race will make it to the finish line at the same time?

I can tell you right now, 80 lbs will make a huge difference in a Yaris, and the 120lb driver will make it to the end first.

[fu_im_from_texas]

I can't tell if you're being sarcastic or not, so based solely on the fact that you haven't been sarcastic in this thread yet, I'll guess that you seem to think both of those cars in your theoretical race will make it to the finish line at the same time?

I can tell you right now, 80 lbs will make a huge difference in a Yaris, and the 120lb driver will make it to the end first.

I agree the lighter car would be faster...not sure that it would be by a large margin though... 80/2300 = .03 or 3%...is 3% that much greater than my less than 1% calculation? ... pretty close...

check out http://www.060calculator.com/

for 106hp and 2300lbs = 9.09 seconds
for 106hp and 2380lbs = 9.33 seconds

1-(9.09/9.33) = .025 or 2.5%

Is it safe to say that lighter rims will increase accelleration by less than 3%? Is 3% a huge difference? or is 3% a small difference? I could make strong arguments either way ...

[Biggie™]

Is 3% a huge difference?

Well, let's step back and look at this with a tad bit wider view. The Yaris isn't a dragster, nor is it an exceptional road racer. But when taking into account the fact it has a steering wheel and brakes, we'll head towards the road race/autoross (along with aggressive street driving) side of things when looking at the benefits of smaller wheels on a Yaris' over all performance.

Take that 3% improvement and factor it into not just acceleration, but braking and turning. In a 0-60 pull, you saved 0.22 of a second. Not really that much time. But that was when looking at less than 10 seconds of performance data.

Now go to an autocross. And for arguments sake we'll say the Yaris ran a 60 second lap. And to make it even more interesting we'll drop the performance gain of the wheels to only 1% do to the fact the car wont always be accelerating, decelerating or turning (even thou it will be doing two of these simultaneously for most of the event). That's only a performance gain of 6/10th of a second overall. But as anyone that has autocrossed knows, that is actually a HUGE amount of time when competing. Now go to a race track where lap times are a minute forty or more and you've just beat your previous time by over a second. Kind of scary when you start to think about it...

[CaysE]

Biggie, I could not have explained it better. :thumbsup:

[fu_im_from_texas]

Well, let's step back and look at this with a tad bit wider view...

of the 6000+ threads on yaris world 41 are under "Tracking, Racing, Auto-X Forum"


... the majoity of yaris owners will not notice a 1% increase in accelleration

[cleong]

of the 6000+ threads on yaris world 41 are under "Tracking, Racing, Auto-X Forum"


... the majoity of yaris owners will not notice a 1% increase in accelleration

First you calculate that there is a small advantage to lighter wheels, then you call it insignificant because it is 0.000-something percent of gain. Then when proven otherwise, you change tack to say that the gain is irrelevant, since we are just discussing an econobox - a car that most Yaris owners don't drive competitively.

So have it your way, install your 17, 18, 19, even 20 inch wheels on your Yaris, it is your car anyway.

But you will see its effects in fuel consumption, and that doesn't fall under tracking, racing and autocross.

[Biggie™]

of the 6000+ threads on yaris world 41 are under "Tracking, Racing, Auto-X Forum"


... the majoity of yaris owners will not notice a 1% increase in accelleration

Well, there are close to 500 threads in the performance section, and most are looking for the ability to accelerate and or deceleration faster. That doesn't even take into account the hundreds of thread concerned with handling. Lighter wheels will improve maneuverability far more than a strut tower brace. So needless to say, the overall improvement lighter wheels give you would actually be interesting to more of this forums members than you first thought. I also used a 1% improvement in my example for the sake of argument. But again, a calculated rotational total reduction in weight of 80 pound from a 2300 pound Yaris is actually 3.47%. So go back and recalculate using that.

Now on to the real fun, I know this will go a little beyond light weight but smaller and lighter are even better... ;)

Using your reasoning, adding weight in the form of big heavy wheels and tires has a negligible effect. So with all the buckets of cash you get from your high paying engineering job, you go out and get some hot new 20 pound each 18X7.5s, for your luxury sport coupe Yaris. You also get yourself some nice 215/35-18s for that sweet low profile look that all the ladies like... Then there's me, with my job in the auto performance and motorsports industry. I go and find myself a set of 8.5 pound 13x7.5s along with some sweet lil' 215/50-13s.

One of my wheels and tires together runs just under 25 pounds each, while yours are coming in somewhere OVER 45 pounds. My tire is 21.46" tall, stock is 23.74"(we'll use this information later) and yours are 23.93" tall. Use this to determine the large amount of energy it will take you to turn your heavy wheel and tire when compared to my lighter and more compact wheel and tire unit. Don't forget most of your mass is almost an inch further out from center. And that's over 20 pounds per wheel and tire unit, using the simplified 4:1 ratio and multiplying it by 4 wheel and tire units we get 320 pounds! Do you still think the majority of Yaris owners will not notice a 7.2% advantage in acceleration, deceleration and changing direction?

Now, with your advanced engineering mathematics, go back up there and use the tire diameters(heights) I listed to determine my improved acceleration do to the lower gear ratio when compared to your slower than stock acceleration and higher gear ratio. And while we are dealing with tire diameters and such, determine the amount of additional energy the stock brakes will need to use to slow your taller and far heavier wheel/tire units when compared to my lil' guys.

But at the end of all this, the ladies love 18's... Luckily for me, I'm married so she'll just have to deal with my nimble little egg shaped ecno-box. And all those equations should keep you busy for awhile. :cool:

[gaffo]

I doubt anything we could get are hands on in a 14 inch or more wheel size would be too light with a tire on it. I've never heard it put that way. I have heard about braking problems with oversized wheels. I think the lighter the better but then strength maybe an issue


MY little Ford Fiesta (German - not the Korean Festiva) had quite a bit of power 1.5 liter, and tiny wheels - 12". The front of the car was too light for the wheels (it was front wheel drive) and on a hard acceleration the wheels would start to "hop" - left then right then left then right (maybe 6 hops a second), like being on a vibrating bed LOL.

So wheels can be too light - but probably depends upon the car of course.

To note, the Fiesta could hawl ass, and ALMOST out accelerate the old bloated 305 8 cylender 1970'/80s Camaros everyone and their dog had in highschool in the 80's...................and the 6-cylender ones were utter DOGS - that Fiesta could beat any 6-banger Camaro easy.

[gaffo]

Well, there are close to 500 threads in the performance section, and most are looking for the ability to accelerate and or deceleration faster. That doesn't even take into account the hundreds of thread concerned with handling. Lighter wheels will improve maneuverability far more than a strut tower brace. So needless to say, the overall improvement lighter wheels give you would actually be interesting to more of this forums members than you first thought. I also used a 1% improvement in my example for the sake of argument. But again, a calculated rotational total reduction in weight of 80 pound from a 2300 pound Yaris is actually 3.47%. So go back and recalculate using that.

Now on to the real fun, I know this will go a little beyond light weight but smaller and lighter are even better... ;)

Using your reasoning, adding weight in the form of big heavy wheels and tires has a negligible effect. So with all the buckets of cash you get from your high paying engineering job, you go out and get some hot new 20 pound each 18X7.5s, for your luxury sport coupe Yaris. You also get yourself some nice 215/35-18s for that sweet low profile look that all the ladies like... Then there's me, with my job in the auto performance and motorsports industry. I go and find myself a set of 8.5 pound 13x7.5s along with some sweet lil' 215/50-13s.

One of my wheels and tires together runs just under 25 pounds each, while yours are coming in somewhere OVER 45 pounds. My tire is 21.46" tall, stock is 23.74"(we'll use this information later) and yours are 23.93" tall. Use this to determine the large amount of energy it will take you to turn your heavy wheel and tire when compared to my lighter and more compact wheel and tire unit. Don't forget most of your mass is almost an inch further out from center. And that's over 20 pounds per wheel and tire unit, using the simplified 4:1 ratio and multiplying it by 4 wheel and tire units we get 320 pounds! Do you still think the majority of Yaris owners will not notice a 7.2% advantage in acceleration, deceleration and changing direction?

Now, with your advanced engineering mathematics, go back up there and use the tire diameters(heights) I listed to determine my improved acceleration do to the lower gear ratio when compared to your slower than stock acceleration and higher gear ratio. And while we are dealing with tire diameters and such, determine the amount of additional energy the stock brakes will need to use to slow your taller and far heavier wheel/tire units when compared to my lil' guys.

But at the end of all this, the ladies love 18's... Luckily for me, I'm married so she'll just have to deal with my nimble little egg shaped ecno-box. And all those equations should keep you busy for awhile. :cool:



Single myself - but if the "Ladies" judge a man by his car:

1. screw em
2. I'm screwed if I'm driving a Yaris - even one with 24" wheels! ;-).

You sold me!!!!!!!!
I know TINY is more fun - period. my tiny 12" Fiesta tires and my 13" Tr7 tires were pure gokart heaven.

Question and recommendations need Sir!

1. that weight you gave 8-1/2 pounds - was that for steel or alluminum (I LOVE Smootie hubcap retro look so have no need for aluminum wheels).

2. any tire/wheel brand recommendations?

3. can we go even smaller on Yaris? 12" maybe?

..................

thank you for such an informative post sir!

[CaysE]

Well, there are close to 500 threads in the performance section, and most are looking for the ability to accelerate and or deceleration faster. That doesn't even take into account the hundreds of thread concerned with handling. Lighter wheels will improve maneuverability far more than a strut tower brace. So needless to say, the overall improvement lighter wheels give you would actually be interesting to more of this forums members than you first thought. I also used a 1% improvement in my example for the sake of argument. But again, a calculated rotational total reduction in weight of 80 pound from a 2300 pound Yaris is actually 3.47%. So go back and recalculate using that.

Now on to the real fun, I know this will go a little beyond light weight but smaller and lighter are even better... ;)

Using your reasoning, adding weight in the form of big heavy wheels and tires has a negligible effect. So with all the buckets of cash you get from your high paying engineering job, you go out and get some hot new 20 pound each 18X7.5s, for your luxury sport coupe Yaris. You also get yourself some nice 215/35-18s for that sweet low profile look that all the ladies like... Then there's me, with my job in the auto performance and motorsports industry. I go and find myself a set of 8.5 pound 13x7.5s along with some sweet lil' 215/50-13s.

One of my wheels and tires together runs just under 25 pounds each, while yours are coming in somewhere OVER 45 pounds. My tire is 21.46" tall, stock is 23.74"(we'll use this information later) and yours are 23.93" tall. Use this to determine the large amount of energy it will take you to turn your heavy wheel and tire when compared to my lighter and more compact wheel and tire unit. Don't forget most of your mass is almost an inch further out from center. And that's over 20 pounds per wheel and tire unit, using the simplified 4:1 ratio and multiplying it by 4 wheel and tire units we get 320 pounds! Do you still think the majority of Yaris owners will not notice a 7.2% advantage in acceleration, deceleration and changing direction?

Now, with your advanced engineering mathematics, go back up there and use the tire diameters(heights) I listed to determine my improved acceleration do to the lower gear ratio when compared to your slower than stock acceleration and higher gear ratio. And while we are dealing with tire diameters and such, determine the amount of additional energy the stock brakes will need to use to slow your taller and far heavier wheel/tire units when compared to my lil' guys.

But at the end of all this, the ladies love 18's... Luckily for me, I'm married so she'll just have to deal with my nimble little egg shaped ecno-box. And all those equations should keep you busy for awhile. :cool:
At the risk of sounding like an ass... OWNED! :eyebulge: :bellyroll:

I'm sorry, fu, I'm not usually a prick... :respekt:

[Biggie™]

1. that weight you gave 8-1/2 pounds - was that for steel or alluminum (I LOVE Smootie hubcap retro look so have no need for aluminum wheels).

2. any tire/wheel brand recommendations?

3. can we go even smaller on Yaris? 12" maybe?

1: Steel wheels are heavy, always run aluminum!

2.a: The tire I basically used in my lengthy example was the 215/50-13 Sumitomo HTR 200. There aren't too many good street tires left in a 13", but you can find some nice race tires(DOT and full slicks).

2.b: There are a number of good looking super light 13" wheels , just do some research and buy what you like and can afford. Here are a few examples. They all wont work for everyone, some have rather low offsets for the Yaris, but they are still usable. I'd recommend the Lenso VPD 13x7.5, 4x100 +25 8-10 pounds? There is also an 8 pound TE37 13X8, 4x100 +20, but those are pricey. Here's a list of even more possible choices. (http://gti-vr6.net/library/wheels_tires_brakes/wheels_weight/wheels2_up_to_13.html)

3: You can't find any good tires in a 12", stay with 13's.


Now, I used a 13" wheel to over emphasize my example. We could easily use a 15" wheel and still get similar results, but with more wheel and tire choices. Lets use a better fitting example for our Yaris.

Enkei RPF1 15X7, 4X100 +41 weighs only 9.5 pounds each.
Toyo Proxes T1r 205/45-15 weighs only 17 pounds each.

Those wheels/tires are 26.5 pounds each and are only 22.2 inches tall, so we still get the low weight, lower gearing and the rotational mass is still closer to center than stock.

[gaffo]

i like the yaris with smaller wheels. I think the ones with the stock 14" look noticably better than the 15" ones.

just me taste. I like the 1950's smoothe hubcap look too. old school VW Beetles really look good with em.

thanks for all the feedback - I'll check out your recommendations ;-).

[Biggie™]

i like the yaris with smaller wheels. I think the ones with the stock 14" look noticably better than the 15" ones.

just me taste. I like the 1950's smoothe hubcap look too. old school VW Beetles really look good with em.

thanks for all the feedback - I'll check out your recommendations ;-).
From the sounds of it, these are the wheels you want. I have no idea what they weigh, and the smallest size they have is 15"...
http://www.work-wheels.co.jp/wheels/index/lsled/click.gif (http://www.work-wheels.co.jp/wheels/index/lsled/lsled.html)

[fu_im_from_texas]

... Yaris is actually 3.47%. So go back and recalculate using that....

You are correct. I rounded 3.47 down to 3%. Sorry for the confusion... my mistake.


...
Using your reasoning, adding weight in the form of big heavy wheels and tires has a negligible effect. ...

I simplified the problem, by compairing 15 inch 16lb steelies vs 15 inch 10lb rims. You are very correct with your 17s vs 13s example ... your 17 vs 13, and my 15 vs 15 are apples and oranges...

Sorry for the confusion, I probably didnt make it clear that the > 1% figure only applied to 15s vs 15s.

:thumbup:

[fu_im_from_texas]

...Then when proven otherwise, you change tack to say that the gain is irrelevant, ....

I claimed that lighter rims would have less than 1% improvement in accelleration. Then, you suggested a 1:4 ratio, which comes to about 3.47 % improvement. Please note that you did not "prove" anything... you simply suggested a different approach ... and I assumed it to be true...

Had I known we were going back and forth over 0% vs 3.5% I would have said "You are right" a long time ago...

[gaffo]

sweet link Biggie thanks!

love the look.

foriegn site - no english ;-/.