Re: [EVDL] Wheels for efficient vehicle.

[Roland via EV]

   
I knew you will get it.  Roland 


- Original Message - 

From: Al Lumas<mailto:ajlu...@hughes.net> 

To: Roland<mailto:e...@msn.com> ; Electric Vehicle Discussion 
List<mailto:ev@lists.evdl.org> 

Sent: Monday, May 18, 2015 2:20 PM

Subject: Re: [EVDL] Wheels for efficient vehicle.



720 / 24 =  30 lbs per square inch.

At 12:54 PM 5/18/2015, Roland via EV wrote:
>One more thing that I did not mention.
>Is the square area of the solid rubber sections of the tire face 
>against the driving surface.  You calculated the square area of the 
>actual contact surfaces of the tire and divided that into the 
>vehicle weight that is on that tire.
>The best way we did this when we were road rally racing, is to ink 
>the tire and than lower it on a white plastic cover board.  You will 
>find that a wide tire will have a narrow foot print about 2 inches 
>long for the width of the tire.  If there is no thread on the tire 
>and the tire is 12 inches wide, then you have about 24 square inches 
>of contact rubber.
>
>  Lets say the weight on that tire is 720 lbs, therefore 720/24 = 3 
> lbs per square inch which is not good for traction.
   

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Re: [EVDL] Wheels for efficient vehicle.

[Ben Goren via EV]

On May 18, 2015, at 12:54 PM, Roland  wrote:

> The best way we did this when we were road rally racing, is to ink the tire 
> and than lower it on a white plastic cover board.

I understand that most track racing uses pyrometers or infrared cameras or the 
like to see which parts of the tire are heating up most, and adjust inflation 
to achieve and maintain maximally uniform load distribution.

I would further suggest that such an approach is ideal for all driving -- 
though, of course, generally impractical. Regardless, if you wish to change the 
dynamics of your tire's contact patch, the only safe way to do so is by 
choosing a different tire. Changing it away from optimal through inflation will 
result in either overinflation or underinflation, both of which can be most 
detrimental to the car's handling.

b&
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Re: [EVDL] Wheels for efficient vehicle.

[Al Lumas via EV]

720 / 24 =  30 lbs per square inch.

At 12:54 PM 5/18/2015, Roland via EV wrote:

One more thing that I did not mention.
Is the square area of the solid rubber sections of the tire face 
against the driving surface.  You calculated the square area of the 
actual contact surfaces of the tire and divided that into the 
vehicle weight that is on that tire.
The best way we did this when we were road rally racing, is to ink 
the tire and than lower it on a white plastic cover board.  You will 
find that a wide tire will have a narrow foot print about 2 inches 
long for the width of the tire.  If there is no thread on the tire 
and the tire is 12 inches wide, then you have about 24 square inches 
of contact rubber.


 Lets say the weight on that tire is 720 lbs, therefore 720/24 = 3 
lbs per square inch which is not good for traction.
  


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Re: [EVDL] Wheels for efficient vehicle.

[Roland via EV]

   
One more thing that I did not mention. 

 

Is the square area of the solid rubber sections of the tire face against the 
driving surface.  You calculated the square area of the actual contact surfaces 
of the tire and divided that into the vehicle weight that is on that tire. 

 

The best way we did this when we were road rally racing, is to ink the tire and 
than lower it on a white plastic cover board.  You will find that a wide tire 
will have a narrow foot print about 2 inches long for the width of the tire.  
If there is no thread on the tire and the tire is 12 inches wide, then you have 
about 24 square inches of contact rubber. 

 

Lets say the weight on that tire is 720 lbs, therefore 720/24 = 3 lbs per 
square inch which is not good for traction.

 

A narrow tire foot print will be longer than 2 inches which a standard vehicle 
tire may be up to 6 inches long and about 6 inches wide.  Again with only solid 
rubber area, the contact patch would be about 6 x 6 = 36 square inches.

 

Therefore the smaller width tire will have more contact area. 

 

We found out that on dry smooth pavement, 10 lbs per square inch will work, 
while on ice, it takes about 50 lbs per square inch to maintain the traction. 

 

Roland 


- Original Message - 

From: Ben Goren<mailto:b...@trumpetpower.com> 

To: Roland<mailto:e...@msn.com> ; Electric Vehicle Discussion 
List<mailto:ev@lists.evdl.org> 

Sent: Monday, May 18, 2015 11:23 AM

Subject: Re: [EVDL] Wheels for efficient vehicle.



On May 18, 2015, at 9:24 AM, Roland via EV 
mailto:ev@lists.evdl.org>> wrote:

> If you use a open spoke wheel that allows air to go thru the wheel, it is 
> recommended to install a aluminum deflection plate about 0.125 inch thick 
> that goes between the wheel and the axil flange, to prevent the air to go 
> thru the wheel.

To save on (unsprung!) weight and expense, a fabric covering might be 
preferable. At least at one point, they were commonly available for bicycles, 
though I haven't seen as many recently. Superficially resembles a solid carbon 
disc wheel.

The basic idea would be a wire hoop the same size as the wheel and a round 
sheet of fabric stretched around it like a drum. Clips on the extremes of the 
spokes can hold the hoop in place. Depending on how the wheel is mounted to the 
axle and the like, you might also need an hole with a grommet in the center.

b&
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Re: [EVDL] Wheels for efficient vehicle.

[Lee Hart via EV]

tomw via EV wrote:

Larger diameter would be more efficient.  If they don't need to carry much
weight you might look into using motorcycle tires which are narrower.


It's not quite that easy. Larger diameter is more efficient, all things 
being equal. But they are rarely equal.


A larger tire and its rim is going to be heavier. The extra weight 
pushes you in the wrong direction.


A larger tire adds wind resistance, both from its larger frontal area, 
and by stirring more air around it as it spins.


The tire may be constructed differently. For example, motorcycle tires 
are definitely not built for low rolling resistance.


Years ago, I talked to Bob McKee about his amazing Sundancer EVs. They 
were going up to 140 miles on a charge on just twelve 6v golf cart 
batteries! He said he did a lot of experiments on tires, and found that 
*smaller* wheels were better, because the weight savings and reduced 
aerodynamic losses were greater than the increase in rolling resistance.

--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] Wheels for efficient vehicle.

[Lee Hart via EV]

Lawrence Rhodes via EV wrote:

MICHELIN ENERGY SAVER 155/65R14 75SES2: This is the best tire I can get from 
Michelin.  Does everyone agree that it is hard to get a more efficient and 
narrow tire?  If this is so what super light rim should I use. If not is there 
a better tire to use.  Each wheel will only have to support 300 to 400 pounds. 
The car or trike will be based on these tires so the rim must be very light.  
Would Insight rims be a place to start?  I'm trying to use off the shelf parts 
so building and maintaining the vehicle will be easy.  Lawrence Rhodes


I have no info on that particular tire. But I do with the Bridgestone 
Potenza RE92 175/65R14 84S XL. This was the special low rolling 
resistance tire that came on our 2001 Prius. When I (and pretty much 
everyone else) changed from this tire to any other, MPG went down by 3-5 
mpg.


As it happens, we just needed to replace the tires on our Prius last 
fall. We bought replacements of exactly this tire from NTB for just 
under $100 each.


--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] Wheels for efficient vehicle.

[Ben Goren via EV]

On May 18, 2015, at 9:24 AM, Roland via EV  wrote:

> If you use a open spoke wheel that allows air to go thru the wheel, it is 
> recommended to install a aluminum deflection plate about 0.125 inch thick 
> that goes between the wheel and the axil flange, to prevent the air to go 
> thru the wheel.

To save on (unsprung!) weight and expense, a fabric covering might be 
preferable. At least at one point, they were commonly available for bicycles, 
though I haven't seen as many recently. Superficially resembles a solid carbon 
disc wheel.

The basic idea would be a wire hoop the same size as the wheel and a round 
sheet of fabric stretched around it like a drum. Clips on the extremes of the 
spokes can hold the hoop in place. Depending on how the wheel is mounted to the 
axle and the like, you might also need an hole with a grommet in the center.

b&
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Re: [EVDL] Wheels for efficient vehicle.

[Roland via EV]

   
To determine what size and load rating that is require for a vehicle, first 
find out what the static load that is on each wheel and tire.  

 

Lets say the vehicle weighs 3000 lbs and the weight distribution is 50/50.  
Meaning 1500 lbs on each axle or 750 lbs on each wheel and tire. 

 

In choosing a wheel, it is recommended to add a percentage over the actual load 
on each wheel or about 1.25% over the load on the tire and wheel.   For are 
example of a 750 lb load rating, choose a tire with a minimum of 1000 lb max 
load rating. 

 

Also choose a wheel with the same load rating as the tire.  

 

Lets say the load rating of the tire is 1000 lbs max at 40 psi, and you only 
have 750 lbs load on that tire, this does not mean to air the tire to 40 psi.  
To determine the best psi setting to use, test the tire deflection rate by 
doing the following test: 

 

Jack the tire off grade and air it up to the maximum psi rating that's on the 
side of the tire.  Now lower the tire to where it touches the ground.  Measure 
from the ground to the rim of the wheel.  Record this measurement.  Now lower 
the tire to the ground putting full weight of the vehicle on the ground and 
measure again to the same reference point.  

 

Lets say it reads 0.5 inch difference between the full load and unloaded weight 
of the vehicle.  The 0.5 inch deflection is about the standard that is use for 
most vehicles.  If the deflection rate is more than 0.5 inch than add some air. 
 

 

Some truckers may use a deflection rate at about 0.385 inch or 3/8 inch for 
smooth highway surfaces to decrease fuel usage.  I have tried the 3/8 inch 
deflection rate, but it gives a very harsh ride and on rough roads, it does not 
allow the tire to roll smoothly over wavy roads. 

 

If you use a open spoke wheel that allows air to go thru the wheel, it is 
recommended to install a aluminum deflection plate about 0.125 inch thick that 
goes between the wheel and the axil flange, to prevent the air to go thru the 
wheel. 

 

Roland 


- Original Message - 

From: Lawrence Rhodes via EV<mailto:ev@lists.evdl.org> 

To: Electric Vehicle Discussion List<mailto:ev@lists.evdl.org> 

Sent: Monday, May 18, 2015 8:10 AM

Subject: [EVDL] Wheels for efficient vehicle.




MICHELIN ENERGY SAVER 155/65R14 75SES2: This is the best tire I can get from 
Michelin. Does everyone agree that it is hard to get a more efficient and 
narrow tire? If this is so what super light rim should I use. If not is there a 
better tire to use. Each wheel will only have to support 300 to 400 pounds. The 
car or trike will be based on these tires so the rim must be very light. Would 
Insight rims be a place to start? I'm trying to use off the shelf parts so 
building and maintaining the vehicle will be easy. Lawrence Rhodes

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Re: [EVDL] Wheels for efficient vehicle.

[tomw via EV]

Larger diameter would be more efficient.  If they don't need to carry much
weight you might look into using motorcycle tires which are narrower.



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[EVDL] Wheels for efficient vehicle.

[Lawrence Rhodes via EV]

MICHELIN ENERGY SAVER 155/65R14 75SES2: This is the best tire I can get from 
Michelin.  Does everyone agree that it is hard to get a more efficient and 
narrow tire?  If this is so what super light rim should I use. If not is there 
a better tire to use.  Each wheel will only have to support 300 to 400 pounds. 
The car or trike will be based on these tires so the rim must be very light.  
Would Insight rims be a place to start?  I'm trying to use off the shelf parts 
so building and maintaining the vehicle will be easy.  Lawrence Rhodes

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