Truck tire pressure is closely related to tire-pavement contact pressure and could be an easy index representing the tire-pavement contact pressure level. To characterize in-service truck tire pressures and truck configurations on Texas highways, a truck survey was conducted on major Texas trucking routes. The survey data demonstrate a significant increase in in-service truck tire pressures in the state of Texas. Analysis of the collected tire-pressure data showed that factors such as axle weight, tire temperature, geographic area, highway class, traveled distance, and axle type are related to the in-service tire-pressure values. In a survey study, a factorial experiment design and a stratified sampling design were used. Analysis of variance, analysis of covariance, and t-tests were used for comparisons of truck tire-pressure data. Laboratory experiments and linear regression were used to identify relationships between the parameters of tire pressure and tire temperature. The survey results for in-service truck tire pressures and the comparisons and analyses of factors differentiating truck tire pressures are presented.