A while back I started a thread about wheel weight vs. acceleration.

http://forums.maxima.org/showthread....s+acceleration

I'm still amazed at the difference in acceleration between my stock 17" AE wheels and Potenzas and my 16" steel winter wheels and winter-traction tires. Ever since I put the winter wheels on my car pulls a LOT harder.

Now, I took everyone's advice that the more the wheel & tire weighs the slower the car will be. Also, the farther away from the center of the wheel that the weight is, the slower the car will be. Makes sense.

So I weighed my 17" stock wheels/tires today @ 47 lbs.
And I weighed the 16" winter wheels/tires and.....you guessed it....47 lbs.

Hmmmmmmmmmmmmmm.

I don't get it. What's the difference? I can't believe one inch would make that much difference. The only thing I can think of is that since the ride seems a lot bumpier with the winter wheels/tires that they're offering less rolling resistance.

So, I've been shopping for new wheels and I've spent all this time trying to find the lightest ones I can afford at the sacrifice of looks. Maybe I should just get whatever wheels I want, as long as they're not heavier than what I have now.

What do you guys think about this?

Sorry so long. Tony

 

Ok the reason your 16's ride so crappy is because they're made for the grabbing the asphalt when there is snow on the ground. Think of them as alterrain tires for your sedan. So when they're is no snow they grap every pebble and stone and anything else that's on the road. Which is why the car's ride is not as smooth as the 17's. As for the reason that your car feels so much more powerful now. That's simple it's because your car is having to work less than it did when you had those wide-*** 17's. The wider the wheel the harder it is to move. So if you get a 17" wheel go with a wheel like any of the Kosei's; that way you will somewhat counteract the problem with the width. But if you go with 16's you will kill two birds with one stone. Your new 16's will ride better and give you better acceleration. I would recommend looking at the tires on the Maxima GXE or the SE with 16's. At least I know when I drove the base model SE w/16's it seemed to ride better than my Maxima SE w/17's. In any case just remember that if you get 16" wheel's to get some that the spokes are flush with the outside edge of the wheel; that way they won't look so dinky. Hope I answered your question and good luck with your wheel hunting.

 

Where did you come up with this? The wider the wheel is the more traction it offers. It's width has nothing to do with how hard it is to rotate. I suspect the original poster is seeing the effects of cold air on his car.

Stereodude

 

How's the Turbo VQ Q working out for you?

Stereodude

 

You got another Max? Thought you had run out of them?

Stereodude

 

OR if you were really serious about high performance you'd get yourself a set of 14s maybe you could even find an old set of 13s. Imagine how light they'd be, and with the extra 20+ lbs of weight saved that 3400+ pound package (you and your car) is gunna really be fly.

 

Well... I think you're attempting to be sarcastic, but each pound of rotational mass is equal to about 8 lbs of static mass. So 40lbs of weight on wheels is fairly substantial.

Stereodude

 

Whow, an 8 to 1 ratio!!! Man I'd always heard saving one pound on a wheel was like saving two on the chassis, so did you really mean to say "8"???

Please enlighten me because what you're saying is, if I save 10 lbs per wheel that's the same as knocking 320 lbs off the total car weight (ie. 10 x 4 x 8)? Now I ain't no engineer and I don't play one on TV or maxima.org for that matter, so I'm having real difficulty with this one. THREE HUNDRED and TWENTY pounds, you've got to be kidding me, I don't think you could convince me it would be the same as 80 lbs, actually anything over 40 lbs is gunna be an uphill battle.

 

Yeah eight. That's what I've been told by others here. There was some debate if all four wheels count on a FWD car (I think they do) or only two. I've not put lighter wheels on my car yet, so I can't tell you what difference it makes. I'll be shaving 10lbs per corner on my car so I'll guess I'll find out if it accelerates like it's 320 lbs lighter or not.

Stereodude

 

I agree with you on the width part. And no, it's not the cold. I had 3K miles to get used to my car before I put the winter wheels on. The minute they were installed and I pulled away from Les Scwabs I felt the difference.

Tony

 

Well, I may have went down one size in wheels, but I went from 50 series on the 17s to 55 on the 16s. So wouldn't that be pretty close to the same diamter (and rotational mass)? And I've pretty much accepted everyone's theory about wheel weight vs. power...but...I totally expected my steel winter wheels and tires to weigh less than the stock 17s, and when I weighed them they were the same. So now I'm totally confused!!

Tony

 

Weight is weight, it doesn't suddenly get magnified 8 times because it happens to be attached to a wheel.

Hey why not try this - put two 160 lb guys in the car with you and go do some 1/4 miles runs and note how much slower you go compared to being on your own. Now dump their fat a**es and put your new wheels on and do some more runs. I'll bet you the price of your wheels that you ain't gunna see remotely close to the improvement from those wheels as you did from getting rid of your buddies. As a matter of fact I bet you'll be hard pressed to actually see a consistently measurable improvement with the light wheels. Not coincidently the improvement you'll see with 40 lbs lighter wheels will be about the same as if you dumped 40 lbs. of weight out of the car.

I will say you can be pretty sure that getting 40 lbs lighter wheels ain't gunna make you go slower, but if you think it's going to have an impact similar to a 320 lb weight loss, well that just plain silly.

 

You answered your own question with your post.
"Also, the farther away from the center of the wheel that the weight is, the slower the car will be."
So, even though they are the same weight, the distribution of mass is different on your two wheels, therefore slowing you down considerbly compared to your 16's. Simple physics.

 

Exactly!

And dont forget, if you switch down to 14" wheels, sure they are lighter and good for the 1/4 mile, but with such large sidewalls they will corner like CRAP! (larger sidewall, more flexing in turns)

 

All right...has anyone done this? Can anyone actually say they really know? I would be very interested to find out. Because if wheel weight if SO important then I'll spend the extra money buying more exspensive wheels that don't necessarily look as good. If not, then I'm buying the best looking wheels for a lot cheaper.

Tony

 

I understand the physics concept of this. My OEM wheels/tires weigh the exact same as my winter wheels/tires. So the only difference is one inch of metal. I have a hard time believing that one inch is going to make me feel like I just added 20-30 hp to my engine. There's got to be something else at work here I don't understand.

Tony

 

"anyone done this" - Yep, did you think I was just making it all up???

"wheel weight So important" - It's just as important as any other weight.

For all those people who are gunna go on about the extra power it takes to accelerate additional wheel weight, I have one word for you - momentum.

While there's no doubt lighter wheels will show more HP on a wheel driven dyno that doen't mean the weight of the wheels is any more important than the weight of the car. Unfortunately the weight of the car doesn't have an impact on the dyno, BUT it does have an impact in the real world which is why we don't race on dynos.

 

Here's some good sites to read and validate for yourself.

http://integra.vtec.net/wheels/lightwheels.html
http://integra.vtec.net/wheels/rotation.html

 

 

Sure it gets magnified. It it's 8 times or 4 times I don't know, it is certainly magnified. It's called rotational intertia. If you don't understand physics there's nothing I can do about it. Try reading the following thread and educating yourself.

http://forums.maxima.org/showthread....threadid=90369
http://forums.maxima.org/showthread....threadid=84255

Stereodude

 

Strictly out of curiosity do you own a Maxima? You post here a lot and "know it all" but have you even driven a Max for any period of time let alone own one?

 

I've been hanging around here since I've been trying to buy a 2K2 6 speed with HLSD. I've been actively trying to buy a Max since the beginning of Sept 01. I've wanted a Maxima for years before that. Alot more time has passed from when I joined than I ever thought would and I still don't have the car yet, so I can't exactly help it that I learned stuff here about the Maxima and now on occasion answer questions about Maximas when I don't own one. I try to stick to things that I have experience with or knowledge about which is why you ususally don't see me answering questions about the specifics of the car.

With all that said no, as of right this moment, I do not have a Maxima of my own, nor have I ever owned one, or driven one for an extended period of time. I did not realize that Maxima ownership was a prerequisite for posting (or posting seriously) here. There seem to be quite a few members of this forum who do not have Maxima or who posted for a long time before they got their cars.

I'm not certain if you're just genuinely curious or if you're about to start the, "Well you don't have a Maxima so you can't possibly know anything about anything related to a Maxima so STFU" treatment and I guess quite frankly it doesn't matter. I've learned a lot here and I'm glad I found out some of the things I did, but it seems from the vibes I get from some members here I'm not welcome here until I have the car in the driveway and can rebuild every part of the car without the service manuals.

Stereodude

 

where the hell did my post go...oh well I had some links about wheels from other tire&wheel sites...this server sucks

and sterodude STFU...J/K

 

I read an article awhile back in Sport Compact Car about rotational inertia, and the effects of unsprung weight. I remember one example was talking about about the effects of a lighter flywheel(i know this is not a wheel), and in the example he said that at launch, a car with a 8 or so pound lighter flywheel will make the car feel something like 325 pounds lighter in first gear, then something like 200 pounds lighter in second gear, and so on and so forth....My numbers are probably way off, but i think you see where i am going with this...A lighter wheel could have the same effect, given that it is unsprung weight on the chassis of the vehicle,(i realize its not in the middle of the drivetrain), maybe not such an extreme example asthe flywheel example, but i think a similair physics concept is at work. The energy required to move the rotational inertia of the wheel is a big power stealer. Like someone said before, the static friction force will be higher for a larger wheel, a heavier wheel, a wheel with the weight farther out towards the edge. So I imagine the 8 poundsof sprung weight is not unreasonable, but on the other hand, it might be that 8 pounds per wheel is only true for first gear, and as the gear ratios change, so will the amount of weight your car feels lighter......I could be totally wrong on this, way off in left field, . I am certainly not an authority or even very educated in physics, but ill try for you guys

 

Stereodude,

Wow. EXTREMELY informative threads!! Thanks a million.

Tony

 

Cool!

 

I suspect you'll need to get yourself some REAL education and stop relying on what you read on the internet as being the gospel truth. I was only attempting to stop a little misinformation from getting blown out of proportion, seems I'm not being very successful. If you want to continue believing you'll get a 4-8 pound advantage from a 1 pound reduction in wheel weight please go ahead a do so, but you'll still be wrong. When you get some actual real world experience I'll be happy to post to the thread you start when you can't figure out why your car doesn't go as fast as you THINK it should. BTW, you're still convientently ignoring the impact of momentum but I guess throwing around big words like rotational intertia must make you feel smart enough.

 

What's your education and background? Do you have an Engineering degree? Have you taken Statics and Dynamics? Maybe even a simple physics class? Apparently not...

Nearly any idiot can tell you that momentum and inertia are almost the same thing. Rotational/angular momentum = the rotational inertia times the rotational speed of the object (omega). If you reduce the inertia you reduce the momentum. You apparently didn't know that, but I'm supposed to conclude that you have even the slightest idea what you're talking about? Hahaha I don't think so.

The moment of inertia for an object is denoted by I. This is equal to the mass of the object m times the square of the radius at which it acts r^2. So if we have a tire and wheel combination that has a mass of 23kg (about 50lbs). The mass acts at a radius of .2meters from the center of mass. This means for this tire/wheel it has .92kg/m^2 of inertia. Now if we have lighter tire/wheel that weighs only 19kg and the mass acts at the same distance of .2m this wheel only has .7692kg/m^2.

Well now... It seems that both the moment of inertia and the momentum of the lighter wheels is less. This means less energy is used to accelerate the lighter wheels which means more energy can be used to move the weight of the car. In effect this makes the car lighter. I could spell it out for you with a long mathematical proof, but you wouldn't believe it anyhow "because it's on the internet".

Stereodude

 

all this physics talk is good but there are a lot of factors that we are not taking into account that the equations stated ignore(yes I am an engineer)

We need to do some experiments!!!!!!!!!!!!!!!!!

Next time you go to the track, switch wheels with someone else's max and report how this affected your 1/4 times! Also bring a scale to weigh the wheels.

Then we will have some numbers that can compare.

BTW do 4th gen wheels fit on a 5th gen?

 

I'm an engineer too. I have no opinion because I don't want to get involved. I like doing experiments and collecting data. It makes my life exciting.

About the 4th gen wheels, yes they fit, but they look poopy. 17" 5th gen wheels look good on a 4th gen, though.

 

In the previous two threads GotRice? voiced his opinions as well as other who have real world experience with lighter rims making a noticable difference on the track and at an autocross circuit. It's not just all theory. There's a reason why nearly everyone who's semi serious into autocross has the lightest rims they can afford (usually SSR Competitions). The reason isn't because they look cool. It's because they make the car accelerate and brake faster.

Stereodude

 

Hey Hogan, so your preparing the bolton kit to go on my max right ? Let me know how it goes, cuz this year I do all the reg mods stuff and next year it is going to be serious one.

Keep in touch.

P.S: are you still moving in CA ?

Cheers

AA

 

No one said lighter wheels didn't make a difference, BUT anybody who thinks knocking 1 pound off your wheel/tire weight will be the same as knocking 8 pounds off the rest of the car doesn't have much grasp on reality, even to argue a 4 to 1 ratio is dumb, 2 to 1 is just about as debatable. Any calculation which shows a gain of much more than 1 to 1 is incomplete.

When I made reference to a "REAL education" I wasn't intending to insult as much as I was intending to draw attention to the fact that real world experience with wheel weight vs. chassis weight will tend to vary significantly from static calculations. There's no substitute for real world experience, unfortunately those without it often resort to incomplete calculations to try to prove their arguements.

 

Yes, but you're not taking one thing into account. If someone is able to shave .2 seconds off in the 1/4 with lighter rims that are a total of 40lbs lighter and they shave off another .2 seconds by lightening the car 240lbs is it not fair to say that the 40lbs from the rims had the same affect as the 240lbs of sprung weight? Would that not make 1lb of rotating mass = to 6 pounds of sprung weight?

Stereodude

 

First of all, ASSUMING all conditions were the same, you still couldn't draw that conclusion since the second .2 gain is going to be harder to come by than the first .2 seconds, not to mention that such a thing ain't ever gunna happen. Secondly, E/T is the wrong measuring tool. Trap speed is a far truer indicator, on par with a dyno only one that takes into consideration real world circumstances.

Most people who test things don't tend to do it all on the same day, and even if you are doing it all on the same day you still need to keep in mind the impact of the atmospheric conditions during each run. Changes in atmospheric conditions can totally skew the results of any testing and looking at E/Ts can be even more misleading since far more variables are introduced.

So I'll say it again...there's NO WAY removing ONE pound from a wheel/tire combination is going to have the same impact as removing FOUR, SIX, EIGHT or TEN pounds from somewhere else on the car. Only in a roadracing context could such a reduction have as much impact as two pounds and this is due more to the unsprung vs. sprung weight issue than the rotational vs. dead weight issue.

I've spent over 25 years racing and have tested more of this sort of stuff than I'd ever like to admit. I've been down the track thousands of times and built stuff that runs in the 7 second range, I've even had a couple feature magazine articles written about my track experiences and records. I talk regularly with a friend who is crew chief for NHRA Pro Stocker Kurt Johnson (ie. son of Warren "the professor" Johnson). I'll spare you the resume, but think it's important to demonstrate that what I'm saying comes from real world experience and not from something I read somewhere on the internet.

Anyway you don't have to believe me, test it yourself. Put on the 40 lb lighter wheels and put 240-320 lbs of friends in your car, make a few 1/4 mile passes and note the results (trap speeds in particular). Now dump the friends, put on the old heavy wheels/tires and make some more passes. There is absolutely NO DOUBT you'll be faster without the friends and with the heavier wheels/tires.

I'm gunna stop now and hope I haven't been wasting my time.

 

My E/T dropped .5-.6 sec in the 1/4 mile after kicking out a 160 lb passenger, so 240-360 lb loss sounds huge! I agree, I don't think it's 6:1 or 8:1 regarding straight-line acceleration.

 

Tell me what you think of this Paul D. I still think there is a greater than 1:1 savings, but prove me wrong, if you can. I posted this earlier and you didnt respond specifically to my guess...No sarcasm here, genuine curiosity. Please respond.

 

ok guys, if I will change my 15's steel wheel set (15lbs/wheel) to lets say OEM 17" SE wheels (28lbs/each) what is the effect on my car. I want gas mileage, dynamics, everything:-)

 

Weight attached directly to the engine's reciprocating assembly is different than wheel/tire or chassis weight, so knocking 1 pound off a flywheel, piston, rod or crank assembly is going to be more significant than knocking a pound off the chassis because it has such a direct impact on the engine's performance. BUT, the engine's performance improvement doesn't suddenly translate into huge HP gains and thus what you see at the track isn't nearly as significant as you'd think. This is the difference between what you 'feel' and what reality turns out to be. I once had Cosworth UK build me a custom billet crankshaft which was 2 lbs lighter than the stock crank I was using (which only weighed 19 lbs to begin with) and while the engine certainly rev'ed up faster it didn't translate to any measurable HP increase and thus the 1/4 mile MPH didn't change measurable. So even in this situation I wouldn't agree with the 8 to 1 ratio because I know knocking 16 lbs off my 275HP 415 lb pro stock drag bike would show measurable differences while the lighter crank didn't. Don't get me wrong here, the lighter chrank was worthwhile because it meant lower stresses on the engine and it certainly didn't slow me down, but the $2500 US I spent on it certainly didn't translate into a great deal of performance. I don't know if that's enough "proof" for you but it certainly was for me particularly when further investigations show that what I experienced wasn't unique.

I think the key to the SCC article is that it said the "weight reduction FELT like 320 lbs", they didn't say "the preformance increase was exactly the SAME as a 320 lb weight reduction" - there's a big difference between those two statements. Personally I'm not interested in how anything FEELS, I'm only interested in what it ACTUALLY does, everything else is just B.S. I'm too old to be doing that bench racing thing so as far as I'm concerned if you can't measure it, it isn't there, and you're just deluding yourself.

I'm sure some people will go out and pay big bucks for wheels that are 40 lbs lighter and then be sure that what they're feeling is something like a 320 lb weight reduction but in fact they really don't know what a 320 lb weight reduction feels like and testing it would only 'burst their bubble' so they ain't gunna do that.

I found it interesting that 'ru4real' mentioned a .5-.6 second change resulted from a 160 lb weight change, I haven't dragged my Maxima yet. This is what I was trying to get at - anyone who thinks knocking 40 lbs of wheel weight off their car is the same as 320 lbs is in effect saying they figure their 1/4 mile time is going to get better by around ONE second with the wheel change. Like I said before, anybody who thinks this has been spending too much time getting an education from the internet and not enough time getting an education in the real world.

No one is paying me for sharing this info and I'm only doing so because I think this forum is useful and wished to contribute something of value to it, but remember you still read all this on the internet so it's value might be questionable :-)

 

Man, I really did not want to get involved but.....

Ok, I have ZERO authority on this topic so don't flame me if i'm wrong, but aren't torque and hp completly different concepts?

Torque being more associated with acceleration and HP being associated with trap speed? Torque is the amount of force being exerted or potential energy, and hp is the amount of work actually done. Thus the faster the engine speed, the more hps it's producing, but the more torque you have, the faster you will get up to the maximum speed of the engine?

(talking out of my *** check)

So, wouldn't a weight reduction in the rotational mass of your wheels free up more available torque to move the vehicle to a faster 0-60 time and 1/4 time but not necessarily a faster trap speed? I'm no physicist but it would seem to me that lighter wheels/tires would contribute to this more than kicking someone out of your car. Perhaps the comparisons here are unrealistic. I don't know about anyone saving 10lbs a corner on lighter rims, maybe 3 or 4. Lets say 4 lb x 8= 24lbs x4= 96 lbs. Of course kicking out a 160lb person who is 64lbs heavier than the weight reduction afforded by lighter wheels is going to make a bigger difference.

Now on the topic of wider vs. smaller I have no idea. But i'm sure the laws of centrifugal force apply.