I recently looked in this wheel stuff, and am happy to share what I learned, and compiled.
What I observed was that the assembly plants tended to be identified by the first letter, and the plant's manufacturing line was the second character;
Plants:
K = Kelsey Hayes
M = Motor Wheel
T = Norris Industries
So your wheel was manufactured by "Motor Wheel", on their fourth line.
Motor Wheel
Your date decoding needs a small correction;
0 = 1970 calender year (correct)
8 = Month; August (correct)
6 = day of month; 6th
Your wheel was made by the Motor Wheel Company, on the 6th of August, 1970.
Curiously, I have notes about that wheel code only being made up until August 1970;
After August, that code wheel was superseded by the code KU, and if my notes read correct, no wheels were made in September or October 1970 because of a strike.
I would wager a guess that the tire on that wheel was changed, as that wheel shows scratching from a trim ring being on, and off of it several times.
I have read period magazine reviews, and read nothing about Stateside tires being replaced for European manufacture tires.