Gack!  The whitewall is ALWAYS on the inside - unless you're from Cleveland,
in which case the whitewalls will match your white belt and shoes...  ;)

On Mon, Apr 19, 2010 at 3:46 PM, Tom Buese <tombuese@comcast.net> wrote:

> On Apr 19, 2010, at 4:32 PM, Sudhir Desai wrote:
>
>> ...................
>>
>>
>> (as far as tire/wheel combinations go, you can always get a lighter
>> wheel to somewhat offset the heavier tire. the stock steelies are
>> pretty heavy, as are the stock alloys)
>>
>
> & you forgot to calculate what brand of tires we should use & whether
> the whitewall is on the inside or outside!  LOL!
>
> YMMV,
>
> Mr. BZ-less is more
>
>
>>
>>
>> I'm not going to offer to do the actual calculations, as I'm sure
>> there is a solid modeler out there that could do ALL of them
>> correctly. (I had to rewrite that email four times because of bad math
>> on my part) ;)
>> Sudhir
>>
>>
>>
>> On Mon, Apr 19, 2010 at 18:07, Jake de Villiers
>> <crescentbeachguitar@gmail.com> wrote:
>>
>>> Nice explanation Suds but... you've left out the other half of the
>>> equation.
>>>
>>>  As the wheel diameter grows the weight of the wheel also grows,
>>> especially
>>> the tire mounting section which is at the far end of the 'lever'
>>> system
>>> which is the tire's diameter.
>>>
>>> So that 5600in/lbs is no longer sufficient to stop the more massive
>>> rotating
>>> 'lever', you need even more brakes.
>>>
>>> On Mon, Apr 19, 2010 at 2:39 PM, Sudhir Desai
>>> <sudhir.desai@gmail.com>
>>> wrote:
>>>
>>>>
>>>> Sorry about the simplicity, I figured I would gloss it over
>>>> HARDCORE.
>>>>
>>>> the 0 represents the hub, the ) the brake rotor/drum, the | the
>>>> outside of the tire.
>>>>
>>>>
>>>> STOCK
>>>> distance of force from hub:
>>>> 0--5"----//---12.5"
>>>>
>>>> direction of force:
>>>> 0--up-------down
>>>>
>>>> illustration:
>>>> 0--)-----//----|
>>>>
>>>> lets say the car is rolling along, and the torque needed to stop the
>>>> wheels abruptly (ignoring/subtracting any sort of rotational
>>>> inertia,
>>>> and friction, etc) is 5000in-lb.
>>>>
>>>> that means, we would have to exert a force of 5000in-lb/12.5in =
>>>> 400lb
>>>> (at 12.5" out from the hub) to stop the wheels abruptly.
>>>>
>>>> now, we go in more to where we can stop the wheels, the brakes. at
>>>> 5"
>>>> out from the hub, that 400lb force needed is now (400lb*12.5in) =
>>>> (xlb*5in), or x = ((400lb*12.5")/5"), so
>>>>
>>>> x = (5000in-lb)/5" = 1000lb
>>>>
>>>>
>>>> SO... to stop the wheel abruptly, we need 1000lb of force at 5" out
>>>> from the hub, and that's the torque our stock brakes can put out.
>>>>
>>>>
>>>>
>>>> when we increase the tire size to a 28" tire:
>>>>
>>>> OVERSIZE
>>>> distance of force from hub:
>>>> 0--5"----//---14"
>>>>
>>>> direction of force:
>>>> 0--up-------down
>>>>
>>>> illustration:
>>>> 0--)-----//----|
>>>>
>>>>
>>>>
>>>> SO NOW WE GO BACKWARDS!!!! lol~
>>>> due to our original assumption of 1000in-lb,
>>>> we have just increased the diameter of our tires to 28".
>>>>
>>>> this means that our 1000 lb force (5000in-lb) that was enough to
>>>> stop
>>>> the 25" tire will not be enough to stop a 28 inch tire by the
>>>> following equation.
>>>>
>>>> 5000in-lb/12.5in = xin-lb/14in, or xin-lb = (5000in-lb*14in)/12.5in
>>>>
>>>> x=(5000*14)/12.5 = 5600in-lb is our new stopping torque needed.
>>>>
>>>> our stock brakes can only exert 1000in-lb of torque, so we won't be
>>>> able to stop the wheel abruptly anymore.
>>>>
>>>> hopefully y'all are following me still...
>>>> we just increased the amount of force needed to stop the wheels, and
>>>> we see that our stock brakes are not enough to do so.
>>>>
>>>> NOW, we need to calculate the size of brakes we need to stop the
>>>> tire
>>>> abruptly (ignoring all other factors).
>>>>
>>>> we take the known stopping torque, and our original brakes (10"
>>>> brakes
>>>> LOL), and see how that compares with our new 5600in-lb
>>>> x-in/5600in-lb = 5in/5000in-lb
>>>>
>>>> x = (5*5600)/5000 = 5.6in
>>>>
>>>>
>>>>
>>>> so we'd need 11.2" diameter brakes to put out the 5600in-lb torque
>>>> needed to stop the wheels abruptly.
>>>>
>>>> which is another inch diameter of brake needed.
>>>>
>>>>
>>>> I hope my simple explanation (with calculations to show i wasn't
>>>> just
>>>> pulling numbers out of the air) was satisfactory. :)
>>>>
>>>> Sudhir
>>>>
>>>
>>>
>>>
>>> --
>>> Jake
>>>
>>> 1984 Vanagon GL 1.9 WBX 'The Grey Van'
>>> 1986 Westy Weekender/2.5 SOHC Suby 'Dixie'
>>>
>>> Crescent Beach, BC
>>>
>>> www.thebassspa.com
>>> www.crescentbeachguitar.com
>>> http://subyjake.googlepages.com/mydixiedarlin%27
>>>
>>>
>>>

--
Jake

1984 Vanagon GL 1.9 WBX 'The Grey Van'
1986 Westy Weekender/2.5 SOHC Suby 'Dixie'

Crescent Beach, BC

www.thebassspa.com
www.crescentbeachguitar.com
http://subyjake.googlepages.com/mydixiedarlin%27