“Because the truck used in the bombing was totally destroyed, an identical Ryder 20-foot truck was used to obtain these known measurements. The truck used was located in Alexandria, Virginia, only a 30-minute drive from the FBI lab, and was one of 400 Ford F700 trucks from that Ryder order. Each of the 400 trucks had sequential vehicle identification numbers (VIN) as well as identical components, including the axles, wheels, and Bridgestone tires.
The truck I examined in Alexandria was therefore identical in all respects to the truck rented by McVeigh. The center-to-center track width measured on that truck was 73.5 inches, the same that had been measured at numerous locations in the tracks in front of storage locker #2. The outside-to-outside and inside-to-inside measurements taken at the scene were not as accurate because the outer and inner edges of the tires were notched and because of the considerable amount of erosion that had occurred due to the rain.
Those measurements, as expected, were 3/8 inch and 5/8 inch off, an insignificant amount under the circumstances. The distance between the tire tracks and the shed door had been measured at the scene and compared against the Ryder truck in Virginia. The clearance that would have remained between the rearmost part of the truck and the storage shed was 17.5 inches on one side and 20.5 inches on the other side. The truck had been backed up to within less than 2 feet of the shed. Figure 14.9A depicts the side view of the truck. Figure 14.9B depicts the rear view with the ramp pulled out.
The ramp was a slide-out ramp built into the rear of the truck. It would only slide straight out, but its width would allow it to fit through the doorway of the storage locker. The fact that the tracks were centered perfectly on the locker door and the truck had backed up so close indicates the ramp was probably pulled directly into the storage locker, not only providing a ramp for loading but also providing privacy. Of all the tracks and track widths that could have been found in front of this locker, rented by McVeigh and Nichols under a fictitious name, these dual assembly tracks were identical to those of the Ford F700 Ryder rental truck that had been used as the truck bomb and had been rented by McVeigh. ”
Extract from Tire Tread and Tire Tire Evidence