anyone know the benifits of lightweight wheels?

[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]

Originally Posted by eTiMaGo

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

eTiMaGo, you are my hero 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.

[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]

Originally Posted by Biggie™

...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...

Originally Posted by Biggie™

... 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]

Originally Posted by 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.

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

[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.

Originally Posted by CaysE

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]

Originally Posted by fu_im_from_texas

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

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]

Originally Posted by cleong

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]

Originally Posted by 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.

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™]

Originally Posted by fu_im_from_texas

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.

[fu_im_from_texas]

Originally Posted by Biggie™

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]

Originally Posted by fu_im_from_texas

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™]

Originally Posted by fu_im_from_texas

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.

[gaffo]

Originally Posted by brickhardmeat

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]

Originally Posted by Biggie™

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.

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]

Originally Posted by Biggie™

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.

At the risk of sounding like an ass... OWNED!

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