I trued 2 sets of new tires on my wheels and kept the PN truer running at 3 volts with very little friction measured by the amp meter showing 2.1 or less. I also stopped often to look at the scuff pattern and not over true. With each set, I trued until it looked ok then ran some laps. Once the track was cleaned a little I got 4.0 second laps. One set took two tries on the truer giving a 0.2 second improvement. I ended up with tires measuring 21.2 mm on one set and 21.0 mm on the second set. No rubber balled up or chunked, but there was plenty of rubber dust on the truer. I still have the dimple on each tire. We should require the dimple at pre-race inspection.;)
I switched the tires between right and left side of the drum during each truing session. It looks to me like the sanding surface on the PN is not consistent across the drum from left to right. The right end looks higher and the left end looks more worn. Do we have replacement sanding covers?