Since when did figures like '77T' or '73T' got related to the HEIGHT of the tire?
The tire wall is denoted by the middle two numbers in the tire size ie, 205/65 R15 with '205 mm' being tire width, '65' being PERCENTAGE of the tyre width (ie. 65% of 205 mm) and R15 being the tire size in INCHES.
Now coming to figures like 77T and 73T. The '77' is the maximum LOAD a tire can bear. 77 is denotes 412 kg i think. Where as the 'T' in the figure is the maximum speed that tire can attain without getting damaged. Hence the load rating has absolutely nothing to do with the tire height/width as per your statement.