Wheels / Tyres yet again
Discussion
Hope to get some feel for what's best for wet / winter weather on my M400.
I'm no expert so any feedback Make Model compound etc greatfully recieved.
I'm going to buy some new wheels and use the originals for winter.
Has anyone here had any experience of Dymags carbon rim wheels?
They claim a standard Porsche GT3 RS 18” wheel weighs about 14kg, the Dymag carbon/magnesium equivalent weighs around 6.5kg saving about 30kg per car!
And that's unsprung!!
They also claim the dynamic advantage is like removing three adult passengers from the car!!
Their mail to me below (abridged version)
The effect on the car however, is much more than the static weight saving. The moment of inertia calculation is based on the ratio of the mass multiplied by the square of the radius, meaning that as the diameter of the wheel increases then the greater the energy consumption of increased weight becomes. Therefore with the Dymag carbon/magnesium wheel the much reduced rim weight has the effect of at least 5 times the static weight reduction, meaning that the feel on the car performance is of taking out 3 adult passengers!!
The effect of carbon/magnesium wheels when fitted to the car is to reduce the gyroscope effect of the wheel this gives the following effects:
1. Improved acceleration
2. Improved braking, reduced stopping distance
3. Lighter, sharper steering, gives better feel and more responsive handling.
4. Allows for softer damper settings giving more tyre contact & therefore better
grip.
5. Tire temperatures and pressures are more stable
6. Improved wheel & tire balancing
7. Fuel consumption reduces
Any comments on the above etc,etc,
F.C.
I'm no expert so any feedback Make Model compound etc greatfully recieved.
I'm going to buy some new wheels and use the originals for winter.
Has anyone here had any experience of Dymags carbon rim wheels?
They claim a standard Porsche GT3 RS 18” wheel weighs about 14kg, the Dymag carbon/magnesium equivalent weighs around 6.5kg saving about 30kg per car!
And that's unsprung!!
They also claim the dynamic advantage is like removing three adult passengers from the car!!
Their mail to me below (abridged version)
The effect on the car however, is much more than the static weight saving. The moment of inertia calculation is based on the ratio of the mass multiplied by the square of the radius, meaning that as the diameter of the wheel increases then the greater the energy consumption of increased weight becomes. Therefore with the Dymag carbon/magnesium wheel the much reduced rim weight has the effect of at least 5 times the static weight reduction, meaning that the feel on the car performance is of taking out 3 adult passengers!!
The effect of carbon/magnesium wheels when fitted to the car is to reduce the gyroscope effect of the wheel this gives the following effects:
1. Improved acceleration
2. Improved braking, reduced stopping distance
3. Lighter, sharper steering, gives better feel and more responsive handling.
4. Allows for softer damper settings giving more tyre contact & therefore better
grip.
5. Tire temperatures and pressures are more stable
6. Improved wheel & tire balancing
7. Fuel consumption reduces
Any comments on the above etc,etc,
F.C.
F.C. said:
The effect on the car however, is much more than the static weight saving. The moment of inertia calculation is based on the ratio of the mass multiplied by the square of the radius, meaning that as the diameter of the wheel increases then the greater the energy consumption of increased weight becomes. Therefore with the Dymag carbon/magnesium wheel the much reduced rim weight has the effect of at least 5 times the static weight reduction, meaning that the feel on the car performance is of taking out 3 adult passengers!!
I'm sorry, but I've never heard so much psudeo science bolloxs in my life (well, actually I have, but this has to rate well up there). He is comparing a rotational force with a gavitational one. If you put the car in space, spun the wheels and then tried to move them up down/left right, you would have exactly the same forces on the wheel with zero, one or 10 people in it.
There is little difference with the same car on the ground from a rotational perspective. There *IS* difference due to the effect of gravity wanting to pull the wheel onto the ground, and hence a lighter wheel requires less force to move up and down, but that is simple F=ma, where a, for most close distances to the earth's crust, is g, or 9.81 m/s^2.
It doesn't matter for that equation if the wheel is 5, 10 or 20" radius.
If their wheels are as good as their science, I'd steer clear.
J
Also discussed at length re Noble application on U.S. forum
www.nobleforums.com/showthread.php?t=1704
The general conclusion is that they only make sense for serious track applications, and indeed may not be a good choice for long term road use.
www.nobleforums.com/showthread.php?t=1704
The general conclusion is that they only make sense for serious track applications, and indeed may not be a good choice for long term road use.
said:
The effect on the car however, is much more than the static weight saving. The moment of inertia calculation is based on the ratio of the mass multiplied by the square of the radius, meaning that as the diameter of the wheel increases then the greater the energy consumption of increased weight becomes. Therefore with the Dymag carbon/magnesium wheel the much reduced rim weight has the effect of at least 5 times the static weight reduction, meaning that the feel on the car performance is of taking out 3 adult passengers!!
LOL
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