Quick update: It's been 20 days since I last put on the initial 3 coats. I live in the Pacific NW rainforest (Vancouver BC) where it's been raining almost everyday. We got a break from the rain on Christmas day but the roads remained wet. I actually don't remember the last time the roads have been dry at all! (We've had incessant rain since early October, sometimes very heavy.) The good thing is that there's been no snow at all. So these tires haven't seen any salt - just lots of rain, dirt and grime!
Haven't washed the tires in 2 weeks and they've lost a little shine, although a lot darker compared to the dirty tires I've seen on the road or parking lot. After washing the van, I gave the tires a quick wash with left-over ONR and a dedicated tire sponge. Here's one of the tires. The shine bounced back and I think it looks great!! That's a tire bombarded by 3 weeks of constant rain. Optimum Opti-Bond Tire Gel (which I've been using for years) doesn't last 2 days in this kind of weather - the reason I don't use it in the winter. Well folks, I think I've found a winner!