I first read of the whitewall conversion back in the 1970s, when having whitewall tires was a status symbol of sorts and expected to happen on upscale vehicles. It seems that a piece of white rubber was in the sidewalls as a normal part of the tire structure. On normal whitewalls, it was thicker and went to the surface.
What some new car dealers would do, to make a few bucks, was order the cars with blackwall tires and then find a local vendor to grind the black rubber down to the layer of white rubber. It did not look as good as the regular whitewalls did, but it was still a "whitewall tire" when done.
One question was raised about taking that much rubber out of the sidewall of a tire--at that time, bias ply tires were the norm. The reply was that not that much rubber was removed so there should be no problems. That was also back when a 8.55x14 tire would typically weigh about 28 pounds (by the old Federal Excise Tax on tires, at 10 cents/pound).
Now, fast forward to the modern P-metric radials. If you go into the manufacturer websites where they might quote tire weights for a given tire size, those tires that used to weigh 28-30 pounds are now weighing about 24 pounds. If you see a modern tire that's blown out and shredded the sidewall, it's very obvious where that weight might have been taken out of the tire.
Personally, knowing how thin those sidewalls are now, compared to earlier times (even for radials!), I would not put "made" whitewalls on anything I had. On the other hand, I suspect that Diamondback is fully aware of those issues and might choose the tires to do that to with a high degree of care. They want you back as a customer and can not stand any problems that might prevent that. In looking at the cut-a-way illustrations on many tire manufacturer websites, I don't think that white layer of rubber is there in all cases, as it used to be, or nearly so thick.
As with any other tire vendor, I suspect that which rep you speak with might make a difference. Key thing is that you get what you desire at a reasonable price for what it is.
Back to the Home of the Forward Look Network