Are heavier wheels making difference in acceleration?

[Croat]

Well after I had the feeling my car was a bit faster and more responsive on the throttle with my winter setup. It was time to put my theory to the test switching to my summer setup. So I made a video. If you want the see the actual diference press play.

 

 

[POWYSWALES]

Surely the change in wheel size changing the ratio is what will be making the acceleration difference.

[Ootohere]

Did you weigh a Winter Tyre / wheel and a Summer Tyre / Wheel to get the weight?

?

What were the size of the winters vs the summers, not just the number on the sidewalls,

 but also actually measured around with a tape measure?

 

http://kouki.co.uk/utilities/visual-tyre-size-calculator 

 

PS,  0-100kmh, is not 0-60mph, it is 0-62mph. But then is the speedo accurate to 100kmh,

probably not with either set of wheels.

Edited 26 April, 2017 by Awayoffski

[themanwithnoaim]

Even if the tyres diameter were exactly the same, lighter wheels will allow the car to accelerate faster.

 

Laws of physics now, stop being pedantic 

[Croat]

40 minutes ago, Awayoffski said:

Did you weigh a Winter Tyre / wheel and a Summer Tyre / Wheel to get the weight?

?

What were the size of the winters vs the summers, not just the number on the sidewalls,

 but also actually measured around with a tape measure?

 

http://kouki.co.uk/utilities/visual-tyre-size-calculator 

 

PS,  0-100kmh, is not 0-60mph, it is 0-62mph. But then is the speedo accurate to 100kmh,

probably not with either set of wheels.

 

Size is:

205 55 16

225 40 18

[Ootohere]

themanwithnoaim,

We know about lighter, smaller etc, other than big tyres on dragsters with power, or going down hill obviously.

Some have been sprinting and dragging for long enough.

 

Nice to know what the weights and sizes were, and also why the car on the video is so damn slow...

 

How much heavier than the 16" steels and tyres are the 18" alloys?

Edited 26 April, 2017 by Awayoffski

[Croat]

Idk I did want to measure them for comparison. But I don't have a scale in my cottage.

But just buy lifting them and putting them in the trunk they are noticeably heavier.

 

EDIT: I forgot to mention my brother was in the car when I was measuring so time is probably a bit better.

Edited 26 April, 2017 by Croat

[Croat]

To be honest I been thinking of selling the summer set and getting rather a 17' one...

[fatzy]

3 hours ago, Croat said:

Well after I had the feeling my car was a bit faster and more responsive on the throttle with my winter setup. It was time to put my theory to the test switching to my summer setup.

 

A very interesting observation, and it matches my theory exacly:

- heavier wheels slows down your acceleration (= more power is necessary to change the rotation speed)

- your summer wheel setup has it's weight longer from the rotation center (= more power is necessary to change the rotation speed)

- less sidewall height gives less grip as it has less flex

- wider tyre has more rolling recistance

- winter tyres has softer rubber, which grips better off the line

- summer tyres was stored for a couple of months and the surface is harder and thereby less grippy

- your winter tyres has a tiny bit less outer circumference, which increases acceleration (but theoretically gives less top speed)

 

All above points in the same direction: yes, your winter wheels will be a fraction quicker!

Edited 26 April, 2017 by fatzy

[Yaumeister]

The amount of movement, for short bumps, is inversely proportional to the weight - a lighter wheel which readily moves in response to road bumps will have more grip and more constant grip when tracking over an imperfect road. For this reason, lighter wheels are sought especially for high-performance applications.

 

Unsprung mass

https://en.wikipedia.org/wiki/Unsprung_mass

[Sec8200]

 A kilo per wheel is approximatelly another 10 kilos more in the coupe. Rule of dumb.

[Ootohere]

What it shows is that Function over style is maybe more important.

What is the point of Sporty Looks if a car is going to be dead slow in the traffic light grand prix.

 

This is what Skoda are now, show without go and no Hot Hatches available to the buying public other than buying a Fabia R5 which has nothing in common with affordable cars for someone wanted a sporting drive.

You can get a big Airport Transport sized Superb with some pace, but that has nothing to do with Motorsport Heritage and Success.

 

Steel wheels and good tyres have a lot to be said for them when driving something that would have trouble pulling the skin off a rice pudding.

[Croat]

This set I have would be ok on a 2.0 TDI or 1.4, 1.8 TSI. But it's killing the 1.6 TDI.

[Jaco2k]

2 hours ago, Croat said:

This set I have would be ok on a 2.0 TDI or 1.4, 1.8 TSI. But it's killing the 1.6 TDI.

 

 You have the 18" Golus, isn't it? If you were nearer... I would have them for my winter wheels

[brettikivi]

Roadtrip!

 

 - Bret

[TDIum]

As someone already said, its laws of physics. Lighter wheels generally are better for several reasons. We are talking about rotational unsprung mass.

Lighter wheels will move faster in response to uneven road surfaces. And for the rotating aspect its not just the mass but where the mass is located - a mech engineer would call this the moment of inertia - think of it like rotational momentum. A wheel with smaller moment of inertia will take less energy to spin up. 

[Croat]

What 17' wheels would you guys pick from Skoda if you were changing yours from 18' to 17'?

[brettikivi]

None. Autec Wizard for cheap and light. 

 

 - Bret

[Petunet]

7 hours ago, brettikivi said:

Roadtrip!

 

 - Bret

 

I'm in. 

[Redboy]

On 27 April 2017 at 10:12, Awayoffski said:

What it shows is that Function over style is maybe more important.

What is the point of Sporty Looks if a car is going to be dead slow in the traffic light grand prix.

 

This is what Skoda are now, show without go and no Hot Hatches available to the buying public other than buying a Fabia R5 which has nothing in common with affordable cars for someone wanted a sporting drive.

You can get a big Airport Transport sized Superb with some pace, but that has nothing to do with Motorsport Heritage and Success.

 

Steel wheels and good tyres have a lot to be said for them when driving something that would have trouble pulling the skin off a rice pudding.

 

Not so sure about show without go. The TSI VRS goes reasonably well, the 245 VRS will be ok. If they made a Fabia 1.8 or 2.0 TSI it would be good fun and I would buy one but in the VAG scheme of things pricing etc they probably have to fit in to the sensible Skoda slot. 

[0ctavist]

Larger tire diameter also reduces your rpm for 100km/h. Possibly, You are then in an unfavorable rpm, which produces a higher fuel consumption.

 

You have to drive the same rpms with the different tires and then compare the different speed and the difference in fuel consumption

Edited 28 April, 2017 by 0ctavist

[Ootohere]

Redboy,

Family / Taxi / Airport transport sized cars with what is hardly modern Hot Hatch pace.

More show than go really, then there are the dirty diesels, even more make them look sporty that will do....

[Jono]

Does unsprung weight really make that much (disproportionate) more of a difference to straight line acceleration?

 

I can understand it's desirable for grip/cornering/braking? but does the fact that it's spinning make more of a difference than it's weight alone?

 

The wheel's net-forwards-movement is identical to the car it's attached to. 

[nidza]

There is a rotational force applied to the wheels from the engine prior they transfer this force to the road, which moves the car.

 

Heavier wheel, more force needs to be applied to accelerate the wheel itself. Same applied to breaking, and this is not insignificant difference. A lot of studies you can find in the internet.

 

Imagine any heavy wheel you turn by your hand, and imagine you try to accelerate it yourself with bare hands. Bicycle for example, small child bike, and huge MTB, there is really big difference in force applied to accelerate it and stop it with your hands.

[Ootohere]

Exactly, I ride a Fat Bike & other bikes with Plus size tyres, not a great deal of difference in total bike weight but the Fat Bike tyres/wheels are a fair bit heavier.

(extra mass)

Once the Fat bike is rolling then the effort to keep going on the flat or down hill is lots less, 'gyroscopic effect'.

The heavier and wider tyres are most noticeable when the tracks start going uphill, but then the gears are chosen to suit this.

(Gravity is a wonderful thing when its aiding the direction you want to go in, fighting gravity can be hard work though.)