The association between vehicle rim type and risk of occupant injury.

OBJECTIVES Modern vehicles generally use steel fabricated or alloy blended rims. The manufacturing process and atomic structure of the rim both yield different responses under destructive loading. The aim of this research was to investigate to what extend the type of vehicle rim may influence occupant injury risk. METHODS A matched cohort study of frontal German In-Depth Accident Study collisions was devised. The risk of injury to various body regions was compared between vehicles with steel and alloy rims. RESULTS Occupants in vehicles with alloy rims were at a greater risk of thoracic injury (relative risk [RR] = 1.57; 95% confidence interval [CI], 1.01-2.42) and thoracic abdomen injury (RR = 1.62; 95% CI, 1.10-2.39) at the Maximum Abbreviations Injury Scale (MAIS) 2+ severity. Risk of thoracic injury was greatest for the cluster of occupants seated on the nonimpacted side in frontal collisions (RR = 2.21; 95% CI, 1.01-4.86). MAIS 2+ injury to the head/face/neck yielded no association (RR = 0.98; 95% CI, 0.66-1.47). CONCLUSION Alloy rims are more brittle and, as a result, destructive loading is realized with less severe impact. The critical failure increases the amount of loading that needs to be distributed by the restraint system and results in injury.