Nitrogen as an inflation gas for passenger car and light truck tires use is widely available commercially. Consumers are confronted with a bewildering selection of offerings, and suppliers tout the purity of their nitrogen generation systems and effectiveness of using the gas in place of air. This paper summarizes some of the touted benefits to a consumer of nitrogen inflation and focuses on those that have technical merit. The costs and other issues facing the nitrogen supply industry are discussed. The paper discusses the physics of gas permeation as applied to a nitrogen-inflated tire and how it differs from an airinflated tire, and applies this analysis to the cost-benefit issues in the nitrogen inflation industry.