The study found that tires under various cargo loads and with varying air pressure could make impressions of varying width. This indicates that when comparing test impressions to crime-scene impressions, tire-impression examiners should not eliminate a tire based only on the impression width when class characteristics such as tread design and noise treatment match. In fact, examiners should expect to find a difference in the width of the contact patch of the impression, especially when there is significant time between the crime and the recovery of the tire. In most cases, the examiner will not know the air pressure setting or cargo load for a tire when it made a crime-scene impression. There may be occasions when an examiner might suspect that a difference in the width of a contact patch may be the result of a larger or smaller size tire than the known exemplar. In such cases, examiners should use the proposed or a similar model of varied tire pressures and cargo loads in order to test the range of variation for the given tire. In addition, consideration should be given to the variables that can cause impression width to vary when performing a tire-track comparison. In order to examine the width of impressions made by tires at varying air pressure, tires were tested under load at pressures of 8, 16, 24, 32, and 40 psi. In separate testing, tire impression widths were measured under various cargo loads at an air pressure setting of 32 psi. 1 figure, 2 tables, and 4 references