Accessory weight 
The combined weight (in excess of those standard items which may 
be replaced) of automatic transmission, electro-mechanical power 
steering, power brakes, power windows, power seats, radio, and 
heater, to the extent that these items are available as factory-installed 
equipment (whether installed or not). 
Aspect ratio 
The ratio of sidewall height to tire width, expressed as a percentage. 
A number of 70 (0.7:1 or 70%) or lower indicates a low-profile tire with 
a shorter sidewall for improved steering response and better overall 
handling on dry pavement. 
Bead 
The part of a tire made of steel wires, wrapped or reinforced by ply 
cords, with the shape and structure to ensure proper fit to the wheel 
rim. 
Bead separation 
A breakdown of the bond between components in the bead. 
Carcass 
The tire structure, except tread and sidewall rubber which, when in-
flated, bears the load. 
Chunking 
The breaking away of pieces of the tread or sidewall. 
Cord 
The strands of material forming the plies in the tire. 
Cord separation 
The parting of cords from adjacent rubber compounds. 
Cracking 
Any parting within the tread, sidewall, or inner liner of the tire extend-
ing to cord material. 
Cold tire inflation pressure 
The tire pressure recommended by the vehicle manufacturer for a tire 
of a specified size that has not been driven for more than a couple of