The research reported on here is concerned with the subject of air flow and temperature buildup in a pneumatic tire. Its ultimate objectives are to understand the basic mechanisms by which energy delivered to the tire is converted to heat, and to quantify the contribution to rolling resistance that is made by this energy-conversion path. Direct measurement of the heat-transfer rate is very difficult, because the tire surface undergoes such large deformations. The approach being taken here is to make measurements of the velocity distributions, and to relate these to the heat-transfer rate by numerical modeling of the flow field.This paper contains experimental results for the velocity distributions. The numerical modeling effort is not yet complete; however, a crude estimate of the heat-transfer rate can be made on the basis of the measured mass flow rates. This estimate indicates that the heat transfer to the contained air is comparable to that occurring on the external surface of the tire.