acceleration vs wheel size and weight

[aucorium]

hi Guys

i have a question i need help on please

I have a set of 17inch mach10 tenzo R wheels, they weigh about 8.7kg's.

most 15inch lightweight wheels are about the 6.5 kg mark ,

my question:

will changing to the 15's make a BIG difference , i know it will make a small diff , but im so use to the bigger wheels , and they look so hot , its a hard choice.

any ideas and comments welcome.

PS , im going to turbo the car next year

:thumbup:

[thebarber]

i think itll make a big difference.

crandall has 17" tenzo R's and i have 14" steelies w/ 185 tires....i notice a HUGE difference in acceleration

ive also put crandalls 15" RS oem alloys w/ tires on my car and didnt notice as much of a change in acceleration as w/ his car w/ 17's

[m911gt]

decreasing your rotational mass is more significant than removing the same amount of weight from a stationary position...so yeah, whether or not you will notice a sizable difference, there will be one.

this is the main reason the lightweight pulleys from NST increase acceleration so well, less rotational mass.

[Loren]

Too lazy to do the kg>lb conversion, but in my experience, on a lightweight car like the Yaris, you'll definitely feel anything more than 3 pounds. Less than that will still make a difference, you just won't notice it as much.

Lighter wheels affect more than acceleration, you can really feel the difference in inertia in the effort that it takes to make a normal stop.

[aucorium]

wow , thanks for all the info guys , i recon i should get tires for the 15inch lightweights i have and give it a good test.thanks for the info , GREATLY appreciated !!!

[thebarber]

Too lazy to do the kg>lb conversion, but in my experience, on a lightweight car like the Yaris, you'll definitely feel anything more than 3 pounds. Less than that will still make a difference, you just won't notice it as much.

Lighter wheels affect more than acceleration, you can really feel the difference in inertia in the effort that it takes to make a normal stop.

its about 19-20lbs for the 17's and about 14lbs for the 15"-ers

youll feel it.

[Loren]

its about 19-20lbs for the 17's and about 14lbs for the 15"-ers

youll feel it.
That's an understatement. 14 pounds to 20 pounds is HUGE.

[ddongbap]

You guys aren't taking into consideration the weight of the rubber. Even though the 15s are lighter, you'll be rocking more rubber weight.

[Loren]

That's a nice idea, but if you look into it, you'll find that it doesn't hold up.

Your average "lightweight" 15" wheel trips the scales at around 12 pounds. Your average "lightweight" 17" wheel is (and I'm being generous) 16 pounds. The weight of the tires is usually about the same. Though for performance tires, because the heavily reinforced bead area of the larger diameter tire is larger, larger wheel's tire will be heavier than the smaller wheel's tire, even though it has less sidewall. Less rubber, more steel.

An when you're talking Yaris tires, the car doesn't need more than 195 treadwidth, but you can't get that in a 17... so you're adding width with the 17, which adds more weight.

Have a peek here and tell me which tire size is lighter, the 15" or the 17":
http://www.tirerack.com/tires/Spec.jsp?make=Dunlop&model=Direzza+Sport+Z1+Star+Spec&tirePageLocQty=

It's always better to go with the smaller diameter wheel if your aim is to save weight. Even 14" wheels would be good if the tire selection wasn't so poor these days.

195/60-14 (typical 18 pounds) on an 11-pound wheel = about 29 pounds.
195/55-15 (typical 19 pounds) on a 12-pound wheel = about 31 pounds.
195/50-16 (typical 19 pounds) on a 14-pound wheel = about 33 pounds.
205/45-17 (typical 20 pounds) on a 16-pound wheel = about 36 pounds.

[33OH]

They've pretty much already said it, but last week I switched from 15's to 17's, and I've noticed minor acceleration and MPG decreases.

[silver_echo]

i run a 205/40r17 and specifically chose that tire size to keep the speedometer correct... well as correct as it can be with a different size... ran the math and it came out to be 0.67 MPH faster at 30 MPH on the speedo

[Loren]

i run a 205/40r17 and specifically chose that tire size to keep the speedometer correct... well as correct as it can be with a different size... ran the math and it came out to be 0.67 MPH faster at 30 MPH on the speedo
Nice. But that's not at all what we're talking about.

[ddongbap]

That's a nice idea, but if you look into it, you'll find that it doesn't hold up.

Your average "lightweight" 15" wheel trips the scales at around 12 pounds. Your average "lightweight" 17" wheel is (and I'm being generous) 16 pounds. The weight of the tires is usually about the same. Though for performance tires, because the heavily reinforced bead area of the larger diameter tire is larger, larger wheel's tire will be heavier than the smaller wheel's tire, even though it has less sidewall. Less rubber, more steel.

An when you're talking Yaris tires, the car doesn't need more than 195 treadwidth, but you can't get that in a 17... so you're adding width with the 17, which adds more weight.

Have a peek here and tell me which tire size is lighter, the 15" or the 17":
http://www.tirerack.com/tires/Spec.jsp?make=Dunlop&model=Direzza+Sport+Z1+Star+Spec&tirePageLocQty=

It's always better to go with the smaller diameter wheel if your aim is to save weight. Even 14" wheels would be good if the tire selection wasn't so poor these days.

195/60-14 (typical 18 pounds) on an 11-pound wheel = about 29 pounds.
195/55-15 (typical 19 pounds) on a 12-pound wheel = about 31 pounds.
195/50-16 (typical 19 pounds) on a 14-pound wheel = about 33 pounds.
205/45-17 (typical 20 pounds) on a 16-pound wheel = about 36 pounds.

I didn't mean that the 17s would be lighter, or the 15 heavier, or w/e. I just meant that the weight gap wouldn't be as big, because rubber also has weight.

[kou]

depending on which tire you buy either 15'' or 17'' there can be 6lbs or more difference.

[silver_echo]

Nice. But that's not at all what we're talking about.

if tire diameter is off, it WILL mess up the gas mileage more than the larger wheel size alone. it will also weigh more to have the 45 series vs. the 40 series.
i will admit that i did take a hit on gas mileage switching to 17's, but in the long run, you need to compare the savings in fuel to what style you like. if you really prefer the look and slightly stiffer handling characteristics of the larger wheels and wider tires, then the difference then becomes an academic argument.

my advice, do exactly what you like with your car. don't even worry about what others think, because opinions are like a**h*l*s, everybody has one.

[ddongbap]

if tire diameter is off, it WILL mess up the gas mileage more than the larger wheel size alone. it will also weigh more to have the 45 series vs. the 40 series.
i will admit that i did take a hit on gas mileage switching to 17's, but in the long run, you need to compare the savings in fuel to what style you like. if you really prefer the look and slightly stiffer handling characteristics of the larger wheels and wider tires, then the difference then becomes an academic argument.

my advice, do exactly what you like with your car. don't even worry about what others think, because opinions are like a**h*l*s, everybody has one.What are you talking about? Numbers don't lie.

[silver_echo]

What are you talking about? Numbers don't lie.

was not saying that numbers were lying... what i was saying was that aucorium is well within his rights to make his own choices... and he had specifically said in his first post that he likes the look of the larger wheels.

[ddongbap]

was not saying that numbers were lying... what i was saying was that aucorium is well within his rights to make his own choices... and he had specifically said in his first post that he likes the look of the larger wheels.

He was asking a question. He wasn't saying one is factually better than the other.

He came here asking questions for answers. We're giving it to him. Good thing this question is easily answered cause numbers are numbers.

But, I kind of think you don't know what you're talking about.

[Doc Zaius]

Leave the noob alone! (We're not talking about overall diameter changes... we're flogging the much-discussed bigger wheels = more weight = less performance on our small cars).

But yeah, Loren's totally right: rubber for bigger wheels definitely weighs more (usually). Those sidewalls don't weigh very much at all. And of course you have to consider that with larger wheels, you're moving the weight distribution further from the center of rotation, which also hampers performance.

I've seen a couple comparisons around the Web, and the "general consensus" is that a reduction of 1lb of unsprung (wheel, tire, brake) weight works out to feel closer to 4lbs of sprung (normal) weight during handling & braking. So if you have larger wheels that weigh 5lbs more each, then that's kind-of equivalent to 20lbs of normal weight, times four for each wheel = 80lbs of extra weight. Not desirable! :tongue:

[aucorium]

hey guys.

seems to be a nice topic to chat about.

well , here is my whole idea behind the question.

1 . i was thinking of putting on 15's to aid my acceleration while the car is NA tuned , but by doing this i loose the whole look of the car the way it is now , but , with the Tein super street coilovers coming soon , that can be corrected.

2.im thinking i should keep the 17's on , and maybe just try and find an even lighter 17inch wheel , as im thinking of going the turbo route and then i recon the 15's will loose grip quite a bit more and 17's might be better.

3.i like the road handling of the 17's and i am a bit worried about loosing that tight road handling feel i have.

4.i want to do a track day or 2 in the near future , so 15's would be better , but i see alot of the guys that run on circuits like Tskuba in japan , think i splet it right , run 17's on the NA tuned 4age and run in general better times than the guys on 15's, but i suppose for a really tight track 15's are better ...

so yeah , thats what been going through my head.

[aucorium]

ps: please excuse the spelling , im switching between windows at work , LOL!