Hmmm... the way this is described, you could wipe out the need for the XL/HL spec just by increasing the load index.
A "99" load index is good for 1709lbs (776kg) per tire. A "103" load index is good for 1929lbs (876kg) per tire. The sum of the 4 tires is 7276lbs, a fair bit more than the...