The overall objectives of this research study may be stated as follows: Determine if surface characteristic measurements can be correlated to wet-pavement crashes in Ohio; Provide improved guidance on the use of ribbed versus smooth tires for pavement surface friction testing in Ohio, including the identification of suggested minimum surface friction numbers associated with each tire type; Provide recommended desirable or target surface friction numbers as a function of site categories and friction demand. Accomplishments of these objectives will help ODOT address their goal of reducing total crashes 10 percent and rear-end crashes by 25 percent by 2015.