Second time darksider needs help!

Well here are the particulars. I ride a 2005 Yamaha Royal Star Venture. I switched a few years ago and installed the Kuhmo Powerstar 758 tire size 165/80 r15. Everything was great, no problems mounting, or handling, just a small problem with maintenance. Lets just say you should take the wheel off each year and lube the splines that engage in the differential. Well, after 38k miles I decided I'm close to the wear bars and its time to replace the tire. The Kuhmo wasn't readily available so I switched to the Nankang cx668, in the same size. I started with the same pressure I ran in the Kuhmo @ 35psi. Everything seemed ok until I got on a road that had rain grooves running with the road and not across the road. It felt like riding on a flat tire. I have increased the pressure to 40 psi with no improvement. I don't think I want to go any higher since that would be more than the sidewall recommended pressure. At this point I am ready to ditch this tire and try and find a Kuhmo again. Can anyone offer any suggestions. Also let me add that I have now put approximately 1000 miles on the new tire. Since I am seriously considering changing the tire, I would also like to know if there is anyone in the Louisville, KY area that I could take the bike to with a new tire and get it replaced. I am from Michigan and I really don't want to ride it back home in this condition. Thanks in advance for any help.

That sounds like the tread design is the problem and no amount of air pressure is going to help. Try uping it and then go down(but not lower than 28 psi) and see if you can make it go away or make it livable. If its still bad I would get a new tire with a different tread pattern.

ROD

I had a Michelin HydroEdge that was a great darkside tire on my VTX, but it would wallow badly on the rain grooves. It was a strange sensation but I just rode through it. Luckly not to many grooved roads around here.

I bought a Kumho tire for my VTX from a Used Tire store for 25.oo. That was two years and about 16K  miles ago and it still has tread left nuff to ride like a hooligan.
See what's in your area.

As for the bike feeling funny on diff road surfaces,...get used to it. There is NO escape.

Well, found a Kuhmo tire and had it installed today. All is good! On another note, I have a nanking tire to anyone who wants it. I am in Louisville, KY. Come and get it and its yours, or pay for the shipping. It doesn't appear to have anything wrong with it. I just didn't like the way it handled.