Had a set of RTs on a Camry. They were not ideal for hard driving and cornering (neither was the car), but they stood up pretty well. As fdcg mentions, the RTs have a non-directional thread and come in large aspect ratios (touring oriented), where the HPs are directional, an have more sizes in lower aspect ratios (performance oriented). I also agree the RT's were comfortable, quiet and I found had good siping/wet performance. I did not recall the tires getting noisier, I'm not sure the RTs I had were made with progressively hardening layers of compound, like the HPs might. Sidewall is very soft on the RTs (and apparently General/Conti's in general according to reviews). One of them actually split a sidewall toward the end of it's life, though I was not driving and don't know what happened. At that time they were replaced with another set of RTs.