Efforts focused on developing recommendations for how to prevent subacute ruminal acidosis (SARA) have identified nonlinearities between time spent below a threshold pH and mean ruminal pH in terms of their interpretation of likelihood of SARA. The goals of this study were to 1) define a relationship between mean rumen pH and time spent below pH 5.8 (TU5.8) and 2) to investigate how diet and cow characterizations influence TU5.8 when formulating a ration for a mean rumen pH between 6.0 and 6.1. Exponential models were fit with mean rumen pH as an independent variable and TU5.8 as the dependent variable. Metadata on rumen conditions were collected from 16 previously published studies (60 treatment means). Nonlinear least-squares regression was used to derive parameters for an exponential curve fitted through the center of the treatment means. Parameters of this curve were used as informative priors for a Bayesian hierarchical model. A Markov Chain Monte Carlo (MCMC) method was then used to sample randomly from each prior distribution and develop posterior estimates for the 2 parameters of our exponential equation: Φ₁ and Φ₂ within each study. Using these study-specific parameters derived by the MCMC approach as independent variables, linear models were fit to predict Φ₁ and Φ₂ using accompanying physical and chemical dietary data from each study. The rate of increasing TU5.8 was 30% greater at pH 6.0 than pH 6.1. The influence of dietary characteristics was determined by changing each parameter ± 1 SD and measuring area under the curve between 6.0 and 6.1 (AUC) compared with the mean diet. The most influential diet characteristics were DIM, CP, and butyrate concentration, changing AUC for TU5.8 by −6.1%, +3.5%, and +2.1% at +1 SD, respectively. Whereas increasing DIM appears to reduce TU5.8 between mean pH 6.0 and 6.1, increasing dietary CP and ruminal butyrate concentrations appear to increase this TU5.8 the most of the variables studied, although other variables were significant. Irrespective of diet, the targeting of mean rumen pH of 6.0 to 6.1, through dietary changes such as forage chop-size, is recommended to avoid SARA.