ABSTRACT
Published information on studies of something so critical to safety as passenger vehicle tire pressures can be found [1, 2]; however, they only account for rolling tires. Studies related to spare tire pressures are lacking. This paper is the result of measurements on 150+ vehicles and the most surprising results are presented regarding the influence of Tire Pressure Monitoring Systems (TPMS) and the new spare tire locations and use. A statistical study was performed on the collected data to determine the correlation between tire pressures, vehicle age and TPMS. One particular topic of investigation was the relationship between various factors that influence spare tire pressure. Some newer models, particularly some mini-vans, have placed the spare tire in an unusual and inconvenient place for regular maintenance. Based on the data collected, TPMS has a positive influence on rolling tires but not on spare tires. The results support the need for TPMS to also monitor spare tire pressures.
CITATION: Popat, J., Nabar, A., Read, M., Fu, C. et al., "A Statistical Study of Tire Pressures on Road Going Vehicles," SAE Int. J. Passeng. Cars - Mech. Syst. 9(2):2016.
INTRODUCTION
For something as critical to passenger vehicle safety as spare tire pressures, public information is seriously lacking. This paper is the result of measurements on more than a hundred vehicles and the most surprising results are presented regarding the influence of TPMS and the new trend toward spare tire locations and use.
Gathering this data is notoriously difficult due to the psychological hurdles involved in gaining access to a trunk that can be embarrassingly cluttered and the time required to measure a tire buried under floor boards. One key observation is that spare tires are often left unchecked or overlooked in between regular vehicle maintenance resulting in safety issues for drivers.
The vehicles sampled ranged from full-sized pick-up trucks to compact cars. The study included vehicle model years from 1965 to 2015 (50 year range). The sampling was performed at the University of North Carolina at Charlotte campus as well as at local tire shops. The tire pressures were measured, recorded, and typically corrected to the manufacturer recommended pressures.
A statistical study was performed on the collected data to determine the correlation between tire pressures versus vehicle age, etc. One particular topic of investigation was the relationship between spare tire location and spare tire pressure. Some newer models, particularly some mini-vans, have placed the spare tire in an unusual and inconvenient place for regular maintenance. Based on the data collected, older vehicles were more likely to have lower spare tire pressures than their newer counterparts, regardless of the ease of access to the spare tire and TPMS has a positive influence on rolling tires but not necessarily spare tires.
THE TEMPORARY SPARE TIRE
On higher end vehicles, there is a trend towards more "Run-Flat" tires. These tires cost more, the vehicle ride is harsher and requires more compensation, and they will not be useful if there is rim damage. With stiffer sidewalls,...