I do use A2Z cleaner when I clean the tires. IMO the Optimum tire shine just doesn't last for me. It looks great the day I apply it, but the next day it looks more matte, then the 3rd day the tires look brown to me. That's just my opinion, not stating it as a fact. I do clean the tires thoroughly before applying any dressing. :xyxthumbs:
That is one thing I like about the Megs #38...it has an anti-ozonate compound in it that prevents the browning effect that I'm seeing. I haven't used a product that is so good at diminishing the browning like #38 is.
PS What do the tires look like after scrubbing? When I was having that problem the tire was brown after it was cleaned, and then the dressing would turn it black, for a shorter and shorter time as time went on. I had to get more agressive with the cleaning--but some of this is an aging process with the tire, with the anti-ozonants coming out, etc.
I thought Optimum was supposed to also have that kind of ingredient. I'm not challenging your opinions or your facts...there are so many variables with tires and dressings, brand/model of tire, age, conditions. I'm just saying I had a set of tires that were fine when they were newer but as they got older I had that problem where no dressing seemed to last more than a few days and the tire would turn brown. I got some of that Hi Temp stuff and mixed it as directed and it kind of scared me because I kept applying it, scrubbing, and rinsing, and the more I did it the more brown gunk came off, and I worried that I was actually doing more harm than good.
Eventually I mixed up a lighter concentration cleaner, and found that if I really did scrub till the brown went away, I got a clean canvas, so to speak. But that's just my experience with these tires, which may have no relation to your situation. I don't find the Optimum Tire Shine to cause browning, but that's just my experience with it.
PS What does the tire look like after you scrub it clean? Is it still brown?