How does the use of winter, all-season, or summer tires affect the accuracy of calculations performed by accident reconstructionists? In this research project, the automotive engineers at Robson Forensic sought to answer this question.


There are many methods crash reconstructionists use to calculate the energy dissipated in the various phases of a crash. The length of skids, yaws or other distances where the primary force imparted to a vehicle is through the tire-pavement interface is a very important component of the overall energy dissipation.

Standard values, based on the performance of all-season tires, are often used for tire to roadway friction, and sometimes modified to account for specific conditions on the roadway. These standard values are useful, but vehicles today are fitted with a wide variety of different types of tires. This study was conducted to test the braking performance of three types of tires to better establish the variances in friction values that should be incorporated into energy dissipation calculations.


Different types of tires vary in carcass, compound, and tread pattern, all of which are optimized for their intended usage. These differences create performance variations in all areas of tire performance, including tire to road friction coefficient.

Valid coefficients of friction are necessary to provide accurate, reliable findings of vehicle speeds from skids. In the testing described in this paper we established adjustments to published data to account for different types of tires that may be on vehicles involved in collisions.

Purchase the complete report from SAE -


Featured Expert

Peter J. Leiss, P.E., C.F.E.I., C.V.F.I.
Steven Becker

​Pete worked as an automotive engineer with General Motors and Dodge. His expertise includes powertrains, suspensions, structures and safety equipment; this includes ABS, Traction Control, and Electronic Stability Control systems.

Pete heads the automotive crash group at Robson Forensic and can help determine which of our experts is best suited to address the technical aspects specific to your case.