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 



----- Original Message ----- 

From: Lawrence Rhodes via EV<> 

To: Electric Vehicle Discussion List<> 

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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