convert your raster data to ascii and save in any of your directory.
then n R

    library(rgdal)
    libray(sp)
    data<-readGDAL("C:/filepath/file")

this will read your ascii grided file
you can also chech your data by varioud commands such as 

    summary(data)

alernatively 
save your raster data as TIFF then using the same package (rgdal) it reads the tiff files
you will read as

    data<-readGDAL("C:/filepath/file.tiff")