Russ – I have previously trued NSRs on my P&N (such as for the NSR rally series) and don’t recall specific problems. But truing the NSRs on the P&N may have made your hubs microscopically oblong, or maybe the tires are just wonky (shifted during the truing process).
For this series – I trued my stock NSR Super-grips (brand new C7R Vette) on the HUDY.
I added Thunderslot ‘foam donuts’ to fill the gap and lightly ShoeGoo’ed the tires.
My Supergrips seem to be shedding/marbling and hence chatter a little in straight line. They also require a good rounding to prevent chatter in the corners.
The Moslers and 917s seemed easier to tune. Today – I can hit 4.1s immediately with my 917. When the tires and motor warm up (50 laps?) it runs consistently in the mid 3.9s without trying.
Both 917 and Mosler have a lower CG and dont have the big caboose as compared to the Vette.
"... get on your bad motor scooter and ride!"
Sammy with Montrose