BlownV8

You car looks amazing. Not a fan or red but it really works on your car.

Tommyboy928

Update on my wheels.

Nutek wheels ,in california . have sendt me wheels that inner and outer part is not even put togeather, back wheels worse thanfron wheels , factory mistake,, and they not answer my e mails or calls, now i been busy last 2 weeks, but will take action as soon i am settled. will also post a youtube video of this disaster,,, my car chake soon apart from 90 kmh and up is direct hopless.. retail 12000 dollars,, should expect its checked for this mistake before they ship them out, that they put them in machine to check for right balance, another thing is they fitted front center part to back wheels ,when they came , we had to switch centers part wheel, back to front . and now impossible balance them out even with best eqment avaliable. is a shame.. but they look good,, but what does it help, when i only can go grandmother speeds ,with a 300 kmh pluss car

sound 8

I tend to agree with you, also I do not want 20 inch rims if they are taking
away power. I used to work in a tyre shop, and never heard of bigger wheels
taking power away. As long as a bigger wheel was fitted with the right size
tyre the gearing remained the same and no power was lost. I can also
understand that turning a wheel from centre to the edge is harder on a big
wheel, however when the correct tyre is fitted the diameter between a big
diameter and smaller is the same. Perhaps your talking weight, in that case
a 25 profile tyre must be lighter than a 30 profile tyre, unless you can buy
special light ones. Can anyone explain
S8

F1BHP

If the over all diameter and weight of the wheel and tire combination remain the same then you will not get any power loss.

In fact in my case I went from 18" to 20" Forged which made the wheel tire combination significantly lighter on each corner despite the increase in size, so actually I would have an increase in power as well as looks.

Sound 8 I have looked at tire weights quite a bit and the weight does come down a little as the profile decreases however not as much as you would think. I assume this is due to extra reinforcements that need to be put into the lower profile tire.

sound 8

Thanks F1BHP for your input, I thought like for like must be similar except
weight. I was going to compromise and put 19 inch rims with 30 profile.
I must admit 20's with 25 profile doesn't give a long distance ride.
S8

Thericker

Not true.. it has to do w/HOW FAR AWAY the weight is from the actual hub, the farther away it gets the MORE you'll loose power. Try for the life of you guys to separate how you think or feel it works, I & multiple others have actually dyno tested these findings & found you LOOSE HP/TQ w/equally weighing 20"s... Certainly the power loss on the dyno wont be as bad as comparing a much heavier set of 20"s to lighter 18"s but what your missing is beyond the small power loss you'll incur w/equally weighing 20"s due to weight of larger 20"s being further away from the hubs is, you're now using an inferior tire w/ skinny sidewalls or aspect ratios vs 18"s you'll be sacrificing any hopes of hooking up from a dead stop & you'll loose the oem handling & especially feel every bump/pothole in the road, also loose oem braking perf, & the major dif besides measuring slight hp loss is, it takes more hp/tq to get you rolling on bigger 20"s vs 18"s so your throttle response will be delayed too, again doesn't matter you've made the 20"s equal in height utilizing smaller tires, the pesky weight shifting further away from hubs causes the car to ultimately accelerate slower period.

But you will no doubt trust your feelings over my & multi others logic & dyno tested info.. Just trying to help here, hopefully this reaches/helps somebody.. Remember it like this, 20"s are Fashion wheels, you're choosing Form over Function, UNLESS properly geared for 20"s or larger from the factory IE they change the gears Ring & Pinion to perfectly work w/ these larger diameter wheels in/on all the newer autos you see these days fitted w/such sized wheels. This makes 20"-up work just like 18"s work on our cars.

sound 8

You are bringing too many things into the equation , diameter, weight,
profile..
Take a 20 inch rim with 25 profile and a 18 inch wheel with 30 profile that
way the same and have exactly the same rolling radius. I can't see that the
20 is going to loose loads of power as you say. I don't seem to be the only
one who can't see why you would loose power, is there a formula to work
out these power losses, or are you going on just dyno measurements which
should prove your right, I just can't get my head round it.
S8.

Thericker

lol enjoy deferring ur inability to understand someone actually knows what they're talking about because u cant get your head around it.. That's about what I expected from you but I thot maybe, just maybe you'd surprise me I wont put it in yet still more simplified layman's terms, enjoy thinking "Just because it doesn't make sense to you" You will refuse my & many others correct explanation/logic & substitute your own corrupt explanation, because its easier for you..

mcguirja

I hesitate to weigh in on this but.... it is about basic physics. I would suggest what is being described in this thread is centripetal force:

"Any motion in a curved path represents accelerated motion, and requires a force directed toward the center of curvature of the path. This force is called the centripetal force which means "center seeking" force."

The formula: Centripetal Force = mass X velocity(squared)/radius

I'm not going to pretend that I know anything about this, but I can understand Thericker's point above. The further away mass is from the radius, the more work there is required to move the object, hence the object will accelerate more slowly - or as described above - need more horsepower to generate acceleration. If I had to develop a hypothesis to prove/disprove I would say the further the rim of the wheel is away from the centre, the higher weight distribution (mass) is away from centre. It will then require more power to accelerate at the same rate. The effect of this would be "robbing" of horsepower as described.

Google Centripetal Force and you'll find there are lots of good explanations of the principle and the application of it.

James

Thericker

yupyup!! my point exactly...

BlownV8

Thericker is absolutely correct. I remember watching a TV show years ago where they swapped tires and rims to larger diamater set. The weight was exactly the same as was the total height/width of new tire combo. They were absolutely stunned when the new wheels lost power. The tuners thought the larger diamater wheels would not lose power just as many of you falsely concluded.

Here are some nifty formulas. http://hyperphysics.phy-astr.gsu.edu/HBASE/cf.html

F1BHP

I don't understand why weight would be moved further from the hub as the diameter is the same. In fact the bit that is furthest from the hub is the tyre which on a 20" setup is lighter, so I would like to see the dyno numbers that compare the same diameter and same weight wheel and tyre as the physics reasoning makes no sence.

BlownV8

It's not reasoning it's fact. Do the math. Having the weight further from the center of the wheel takes more power to turn the wheel. Wheel diameter absolutely has a huge effect on power.

sound 8

Why do you have to bring insults to an interesting discussion. You should be above this Not many enthusiast understand this subject, but instead
of explaining it , you just want to sling insults. Other members seem to think
the way I do. The distance from the hub to the edge is the tyre edge, so
the weight of the tyre must make a difference. Also a lightweight 20 inch rim
must be easier to turn than a heavy 18 inch. But as I say there is the tyre
which increases the diameter. I think this is a personal point, the fact you have 18 inch wheels and you hate fashion 20 inch wheels means you must
prove that 20 inch wheels will rob you of power. You seem to get hot around
the collar when members mention their new 20 inch wheels.
Lastly does the motor trade know about this, because most new cars are getting bigger diameter wheels, thousands of horse power lost....
S8

sound 8

Thanks for the explanation, the further weight is away from the hub the more difficult it is to turn, well that's the tyre, so if the diameter is the same
and the weight is the same how can the wheel size make a difference.
I have a friend wwho works for Williams F1, he is very busy but I will ask
him to simply it.

F1BHP

I do understand that weight further away would be more difficult to rotate however what I was saying was that with the same diameter wheel and tire combo this would not always be the case.

In fact the part that is furthest from the center would be the tyre, which is in fact lighter.

This would lead me to believe by taking the theory that Thericker and Blown V8 have put forward, (which I agree is correct) a larger wheel with a smaller profile tyre with the same overall weight, could in fact have less weight further from the center which would mean it would create more power than the smaller wheel equivalent.

EDIT

So although what I said above could be correct, it would not apply on every wheel setup

Going over this again, I think that it is also wheel type dependent as different wheels of the same size and weight may distribute the weight differently, some may use a lighter barrel and thicker spokes for support and some may go the opposite way which will alter the mean weight distribution from the wheel center.

This may also apply to tires, with some using more material in the sidewalls than others for example.

No doubt the best thing is to reduce the overall weight as much as possible however this in my case is lightweight 20" wheels as I cannot clear my 405mm brakes with anything smaller.

Thericker

S8 you are reading something I didn't write Show me 1 insult?? I'm merely frustrated w/ur inability to defer to someone/hell an entire group of people who knows more than you on the given subject.. Chill out...Did you actually read my entire post errr?? I went in depth on exactly how new/er autos w/20"s+ work PROPERLY it's called proper GEARING the Ring & Pinion is in these cases made shorter vs our cars w/super tall gearing.. When you change any wheel/tire combo from factory & say make it even slightly taller you're in essence changing that gear ratio yourself to the negative end IE making the car slower...

Here's the part of my post from above that you obviously missed in your speed reading/skimming SLOW down & read before wasting everybodys time reexplaining everything ad nauseam..

Seriously S8 I & countless others have had so many bad interactions w/you, you don't understand something & argue to 9th degree until we break it down enough for even a 16 yr old cheerleader to become an expert on the subject & ruin countless threads etc (That was a veiled insult btw lol) I'm putting you on ignore go hassle someone else...

sound 8

These as far as I am concerned are insults " ur inability to understand..
That's what I expect of you..maybe you'd surprise me .."
These are referring to someones intelligence , and if I were talking to you
about a subject which I knew and that you did not know, I would not treat
you like someone thick, look at all my posts I don't insult people , it's called manners. You went overboard on this subject making out you would loose
huge amounts of power with 20 inch rims.

Well after speaking to someone who is an expert, explained it to me easily.
He said when you add a tyre ( weight ) to an 18 inch wheel it will be easier
to turn than putting a tyre on a 20 inch rim because the weight is further
from the hub. He also said the difference is minimal, and not as huge as you
say,
S8

sound 8

This is what you said ,GIANT LOSSES doesn't mean 10,20, even
30 hp, it means 100 hp. And yet you say 20's oem on new cars are OK.
I don't think any one could get their head around this sort of loss just by
changing their 18/19 wheels to 20's, and lets face it thousands of SL owners
have or are going to buy 20 inch rims. I think you went a bit over board on
the figures, which as a professional has told me has minimal affect.
S8

Thericker

No it means/meant what I saw on the dyno 30 whp on avg.. But in that particular cherry picked quote of mine I was ref another member using giant very heavy & wide 20"s if memory serves 20x13-20x13.5 in rear on 345's very similar to my outgoing set that weighed close to 70lbs ea in the rear, I saw a 40 odd whp loss vs stock 18"s I even note 40+whp in that quote how could you think it means 100+ whp ???? You/sir/madam are an absolute life sucking waste of time for the last time STFUP & go hassle some other forum What is your major malfunction? you are so confused/scrambled it's beyond reason yes those are insults enjoy ur day on your 5th-6th SL I'm certain in 5-6 mo you'll complain about this latest purchase & sell/trade it for another etc & make a whole new list of ridiculous frivolous complaints & Q's about it w/umpteen new worthless NEVER ending threads..

You NEVER add anything of value to this forum, its always a complaint/rant or NEVER ENDING question you demand the general pop here to break it down to you like a child as you are just a helpless SOB.. I & plenty others here add value IE new mod info, how too's, help others find deals on mb parts etc etc, What do you do besides complain & ask litany of mostly basic stupid Q's ????


Here's an analogy for the mentally challenged to try an understand that even if the weight is the same, the further the weight of biggest part of the wheel (The Barrels & spokes) is shifted from the center (hubs) it takes more hp/tq (power) to get the same original mass = wheels/tires & ultimately the car moving. Tie a nut/bolt to a string, 1 string @ 18" the 2nd string @ 20" now try swinging that over your head like a slingshot, tell me how much EASIER it is to INITIALLY get the SHORTER 18" string w/same nut/bolt swinging continuously over your head (Bulbous mass on top of your shoulders) vs swinging the 20" string w/same or equally weighing nut/bolt. Even you should see the light now.. As I previously said on my 1st lecture "Physics for Tards" It effects your throttle response too, IE initially getting the car rolling/moving from a dig...

sound 8

WHoops touched a nerve by your reaction..
I have been on this forum for a long time, and I have tried to help members
as well as show my car and equally congratulate others on their latest
acquisition . You know about cars but in this case the words Giant Losses
obviously made me worry about my power, so I took the necessary action to
find out more.
If my threads bother you, then you go and find another forum.
S8

BlownV8

People pay thousands of dollars for 40 RWHP. I guess we are just arguing semantics. To some it's huge to others, not interested in power, it's not. Once again, Thericker is absolutely correct. Wheel size can and will make a huge difference in power.

sound 8

You right 40 whp is not to be sneezed at, but I think it needs someone
to actually carry out a proper test, perhaps an organisation. I don't think
you can say 20 inch looses 40, so 19 inch would loose 20 and on and on,
it needs to be more technical under supervised conditions instead a member
carrying out the tests. Most SL's are turbo or supercharged, if you loose
power by fitting bigger wheels, increasing boost pressure by a tiny amount
will get it back. Fear not all you 20 inch owners, all is not lost.
S8

sound 8

Hi, I agree with you, we are talking about wheel diameter, and a 18 inch
wheel will be easier to turn than a 20 inch, however we do not drive on the
rims
As soon as you fit a tyre the diameter increases, so if the tyre is light on a
20 and heavy on an 18 I can't see why you would get more power from the
18 inch rim. When does a wheel become whole, surely after the tyres are on. I can see small losses but not 40 hp.
S8

BlownV8

Do your own dyno tests. You will be surprised at the loss in power. It's where the weight is located that is killing the power. A 20" wheel is going to have more weight toward the outside of the wheel than the 18" wheel given the same overall height and width of the rim/tire combo.

Now, if you were arguing a low profile 20" wheel and tire combo makes more power than a large 18" off road truck tire combo you would be correct.

I'm really surprised at many posts. Many ask questions and people share real world experience backed by physics and those same people asking the questions choose to ignore the answers. Not really sure what to say.