Even a pH 5.0 acid with a dilution rate of 4:1 (as recommended by Meguiar's for their Wheel Brightener (Ammonium hydrogen fluoride [NH4] [HF2]) results in a pH 4.5 solution. The dilution of an acid doesn’t make it safer as the addition of a molecule of water to a chemical compound, without forming any other products is known as hydration (i.e. dilution causes the pH to decrease) But since pH is not a very good indicator of the strength of the acid in every system, this approach won't always produce the desired results.
Wheel Cleaners-
Wheel Cleaners:
Acid wheel surface damage -
Boxster Wheels looking grim - Detailing World