Obviously not familiar with caliber designations.
A "caliber" is an archaic unit of measure for designating the diameter of holes, where 1/100th of an inch is 1 "caliber".
.01" = 1 caliber
.224" = 22 caliber
.257" = 25 caliber
.308" = 30 caliber
.500" = 50 caliber
et cetera, ad infinitum.
So a truck 50" wide would be roughly 5000 caliber, if you chose to use the measurement of the cab width.