Shinko 244's and speeds above 60 - death wobble

[fjmartin]

I recently put on a set of Shinko 244's on my RX3. 5.10-17 on the rear and 3.00-18 on the front. Tubes are standard IRC...not heavy duty. I have a wheel balancing stand and got them perfectly balanced. I have the proper tire pressure for road riding of 33 rear and 32 front, I have verified that the chain tension is good and that the rear wheel is straight and that the axle nuts are torqued to 55 ft-lbs. They ride fine until I get up to freeway speeds around and above 60. They bike starts to do a wobble (slightly swinging left and right) which in the bicycling world we call a death wobble as it can get out of control and cause a crash. It goes away if I let off the gas and bring the speed down below 60. The OEM CST tires did not have this issue.

The only thing I can think of is I did not powder the inside of my tire and maybe the tube has a twist of something in it?

Any ideas or experiences that you can relay?

Thanks much!