The speed Cesar Martinez, Jr. was traveling was in excess of the posted 55 MPH speed limit, in wet road conditions. His perception and reaction time, puts him in what is called the dillema zone. A zone that describes where a vehicle is located in reference to its given traffic signal light and the engineered posted speed limit. Drivers are more likly to run a changing yellow traffic signal or stop.
This document shows the speed difference of the tires installed on Cesar Martinez Jr's truck. The top speed his CDR recorded was 56 mph = actual 69.84 mph. In a 55 mph zone, on wet road conditions.