How much slower will my car be with 17inch monoblocks?

[golden1245]

Hey guys, so some of you may remember me thinking about upgrading to some 17inch AMG wheels.

When it comes down to it, I care more about acceleration performance than looks, even though some monoblocks would look amazing on the car and increase its handling capabilities.

Would acceleration decrease considerably if I upgraded to a set of 17inch non-staggered monoblocks? I agree that out of all the wheels out there, the monoblocks look best on the w202. There just seems to be so much wheel on them though, it's like a chunk of metal. They look really heavy.

My 230k is surprisingly zippy and I'd like to keep it that way, it accelerates, enters freeways, brakes and passes cars quite well with the original 16 inchers.

Thank you in advance for reading

[renault12ts]

You'd never notice, even if it did.

[DSM10000]

For a body with constant mass, the acceleration of the body is proportional to the net force acting on it. Force = Mass x Acceleration so Acceleration = Force/Mass
See Newtons second law of motion.

The only way you will change acceleration is by either changing the force (i.e. power and torque) or the mass of the vehicle.

[mct_cars]

In theory, setting off from a standstill might be faster....... more grip.

[Red C220]

Originally Posted by DSM10000

For a body with constant mass, the acceleration of the body is proportional to the net force acting on it. Force = Mass x Acceleration so Acceleration = Force/Mass
See Newtons second law of motion.

The only way you will change acceleration is by either changing the force (i.e. power and torque) or the mass of the vehicle.

Response of the month.

Does an extra Inch make a difference?

Newton says no.

For some reason that response tickled me.

[renault12ts]

You could argue that the greater mass of the 17 wheel would spin more slowly to speed, and thus effect acceleration...but you just wouldn't notice on a road car.

[DSM10000]

Originally Posted by mct_cars

In theory, setting off from a standstill might be faster....... more grip.

Newtons second law is considering 3 elements, you are adding variables. In practice we know gearing, road surface, driver etc can and do affect acceleration times to a degree but in absolute terms acceleration is governed by the force available to accelerate a given mass.

[renault12ts]

Originally Posted by DSM10000

Newtons second law is considering 3 elements, you are adding variables. In practice we know gearing, road surface, driver etc can and do affect acceleration times to a degree but in absolute terms acceleration is governed by the force available to accelerate a given mass.

Its a variable which does effect the acceleration of the car...but insignificant in this instance. Is the 17 wheel and tyre heavier than the 16 inch (probably), then I'm sure, in extremus, the heavier will spin up to speed more slowly. I'm being pedantic, because as I said right at the beginning you wouldn't be able to tell.

[DSM10000]

Originally Posted by renault12ts

You could argue that the greater mass of the 17 wheel would spin more slowly to speed, and thus effect acceleration...but you just wouldn't notice on a road car.

Why would a 17 inch wheel have greater mass than a 16 inch wheel? it depends on the materials from which they are made.

[DSM10000]

Originally Posted by renault12ts

Its a variable which does effect the acceleration of the car...but insignificant in this instance. Is the 17 wheel and tyre heavier than the 16 inch (probably), then I'm sure, in extremus, the heavier will spin up to speed more slowly. I'm being pedantic, because as I said right at the beginning you wouldn't be able to tell.

Absolutely but we just need to know what is being compared, 17 inch wheels made of titanium compared to 16 inch wheels made of steel would probably lower the overall mass and therefore improve acceleration although as you say probably unnoticeable in real life.

[renault12ts]

Originally Posted by DSM10000

Absolutely but we just need to know what is being compared, 17 inch wheels made of titanium compared to 16 inch wheels made of steel would probably lower the overall mass and therefore improve acceleration although as you say probably unnoticeable in real life.

I assumed that we were comparing wheels made of like materials.

But, anyway, to the OP...don't worry go for the 17s if you like them.

[flanaia1]

Originally Posted by Red C220

Response of the month.

Does an extra Inch make a difference?

Newton says no.

But his wife said yes

[hotrodder]

Originally Posted by golden1245

Hey guys, so some of you may remember me thinking about upgrading to some 17inch AMG wheels.

When it comes down to it, I care more about acceleration performance than looks, even though some monoblocks would look amazing on the car and increase its handling capabilities.

Would acceleration decrease considerably if I upgraded to a set of 17inch non-staggered monoblocks? I agree that out of all the wheels out there, the monoblocks look best on the w202. There just seems to be so much wheel on them though, it's like a chunk of metal. They look really heavy.

My 230k is surprisingly zippy and I'd like to keep it that way, it accelerates, enters freeways, brakes and passes cars quite well with the original 16 inchers.

Thank you in advance for reading

They are really heavy.

Originally Posted by mct_cars

In theory, setting off from a standstill might be faster....... more grip.

Tyre grip is horrifically complicated involving slip angles, contact patch size and shape etc. Fitting wider tyres doen't equate to more grip. Gross generalisation but for a given vehicle weight and tyre pressure fitting a wider tyre changes the shape of the contact patch making it shorter and wider, not larger. Lowering the tyre pressure increases the size of the contact patch which is why drag racers do it. Short wide contact patches can give better grip at the limit under cornering but they also break away faster and with less warning when that limit is exceeded. They can also result in more tramilining, less grip in slipery conditions and more rolling resistance + noise which = less fuel economy

Originally Posted by DSM10000

Why would a 17 inch wheel have greater mass than a 16 inch wheel? it depends on the materials from which they are made.

Yep but many alloys are more about looks than perfomance. In some (many?) cases for a given size a steel wheel can be lighter than an ally wheel. While the steel wheel may be lighter than a cheap/stylish cast ally wheel of the same size it'll be heavier than an ally wheel that has had the weight designed out of it (forged instead cast, spoke design based on engineering first, appearance second)

Switching from the stock 15x7 with 205/60r15 to 17x7.5 AMG II with 225/45r17 on my w124... Rolling circumference is kept as close as possible, the AMG wheel/tyre combo is more than 5kg heavier per wheel over the stock MB 8 holes. Most of that is in the wheel, some in the tyre. The difference is enough to notice in fuel consumption (virtually all of that'll be to do with extra drag from wider tyres). Under the right conditions a stopwatch might just be able to tell the difference but the usual 'seat of the pants dyno' won't stand a chance of noticing. The extra weight also messes with sprung - unsprung weight ratios. Not a big deal on a heavy old MB but a big deal on something lightweight as it messes with suspension performance, both ride and handling

[A17 LTF]

I have recently fitted 17" monoblocks on my W202 C200. I originally had 15" steels with wheelplates on. I now find the steering much lighter and have not really noticed much change in the performance of the car.

[moonloops]

The overall diameter of the wheel and tyre combination can make a difference to acceleration (and speedo readings). Newton can FO