Vehicle normal load on the tire 
The load on an individual tire that is determined by taking each axle's share of the curb weight, accessory weight, and normal occupant weight (distributed according to the table below) and dividing by 2. 
Wheel size designation 
Wheel rim diameter and width. 
Occupant loading and distribution for vehicle normal load for various designated seating capacities 
 
Designated seating capacity, number of occupants Vehicle normal load, number of occupants Occupant distribution in a normally loaded vehicle 
2, 3, or 4  2  2 in front 
5  3  2 in front, 1 in back  
Tires and vehicle load limits