Test ll for TPC. After successful first test I applied TPC to a second car this weekend. Using the same cleaning regimen - spray concentrated Power Clean, allow to dwell, rinse with ONR, then repeat. After a final rinse with ONR, I allowed the tires to dry completely. Using an old microfiber, I applied TPC to the tires but immediately found it hard to spread evenly. These tires are year old Continentals and they have fine ribs. It was hard to get product into the ribs and it dried blotchy - not sure if that was a cleaning issue or uneven product application. I tried a 2nd coat to see it evened up, even trying an up & down motion to fill ribs, but no joy. I didn't get the ugly discolored blotches I've seen in photos, just an uneven color distribution, so it's possible I didn't get the ribs as clean as necessary. All in all the tires look better and I'll be curious how durable the coating is, but the blotching is discernible to someone even partially anal (like me). My last car also has Continental tires with ribs...so I will REALLY focus on thorough cleaning before application. Optimum recommends applying TPC with an HVLP gun (10 psi and .08 needle) that could allow better coverage in ribs. I don't have one and unless Dr G wants to supply it, I will have use the towel.) I will also use more product to try to soak those ribs.