Do you guys know the cost of the tires on the new roadster? The veyron can do 250mph+ and those tires cost $40k. I was just curious if roadsters will be that much also.
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If you search this forum for the word “tires” you will find that the tires on the red Roadster prototype (the only one seen driving on public roads so far, I believe) are Michelin Pilot Sport Cup 2 tires, 325/30ZR21 rear and 295/35ZR20 front. You can search a site like tirerack.com to find current pricing. Far less than $40K.
40k !!!! I've had a heart attack are they lined with gold acoustic foam?
I remember reading somewhere that the tires were expensive because they had to have them at a certain exact pressure (something like 3 decimal places) psi to ensure safety at high speed.
Also, I ready that they were glued on or something similar, requiring special process, labor, blah blah blah
There's probably a sign in the service center that says "whatever the actual price of service is, increase by $39,500"
Yes and those tires will last about 10 minutes at top speed on the Veyron. Cup 2 on the Roadster prototype is much cheaper than that although it is not known whether you car drive at 250 mph with that.
The tires are experiencing over 3000 Gs at 250mph. That takes some special engineering to keep them from disintegrating. I do not expect the car to reach that top speed with its standard tires it's driving around now. But we'll see.
I just hope Tesla also realises that a sports car, super car, hyper car, halo car and whatever new category this is in, is not just about top speed and straight lines (like the Model S kinda is). It needs to corner as fast as electricity, to quote Jeremy Clarkson
Got this from several documentaries and car reporting websites. One of them quotes "Imagine the engineering that went into the tyres alone? Michelin had to develop a compound that can deal with 261mph any time the owner of the car wishes. At full speed the edge of the tyre is subject to 3,800 G's, but equally this car can be driven as easily as any grand tourer and so the tyres need to also be capable of displacing standing water, complying to road noise regulations and coping with the lateral loads of a car that is over twice as powerful as a Ferrari 488 GTB." But there are many more that quote the 3000+ numberTotal curiosity question:
f=mv^2r or m=f/(v^2r)
250 MPH = 112 m/s
Tire radius (325/30R21) is 0.3642
Force is 3,000G = 29,400N
How did you settle on 0.85kg for a tire mass?
Total curiosity question:
f=mv^2/r or m=f/(v^2/r)
250 MPH = 112 m/s
Tire radius (325/30R21) is 0.3642
Force is 3,000G = 29,400N
How did you settle on 0.85kg for a tire mass?
Edit, it's /r not *r, numbers are right though
It's a more complex integral calculation than this because the mass of the tyre is not all at a single point on the outside diameter. So you can't treat it like a point mass moving in a circular path.
OK, now I'm really confused by this. I was assuming (with my limited knowledge) that they were talking about centrifugal forces, maybe instead of outwards only with the combination of the forwards directed rotational vector. But you're talking about centripedal force, which is a totally different direction.Oh, i understand that, but the use of Gs as the unit means acceleration is being expressed, and on a quickly rotating tire in a straight line, the major acceleration of note is centripetal. The stresses in the sidewall and tread would be a force in Newtons, which would then require a mass to convert to Gravitys. So you would need a physical crosssection or such to take the mass of to convert those forces to Gs.
Running though the calculations with more coffee, I realized I forgot to cancel out mass when going from Newtons to Gs.
f=m*v^2/r (centripetal)
f=ma
so
ma=m*v^2/r
or
a=v^2/r
In other words, acceleration is independent of mass
v=112m/s (250MPH)
r=0.38m (325/30/R21)
a=34,295m/s^2
1G=9.8m/s^2
a=3,500 G
All makes sense now.
OK, now I'm really confused by this. I was assuming (with my limited knowledge) that they were talking about centrifugal forces, maybe instead of outwards only with the combination of the forwards directed rotational vector. But you're talking about centripedal force, which is a totally different direction.
I could be wrong but I think they are just saying you don't want this to happen.
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