See if you can video a run and play it back in slow motion I'll bet your wadding the tire up on the launch, try some more air pressure, my Stocker use to do that with 9x30x15 Firestone bias plys at 13 to 15 lbs pressure(tubeless), rasing the pressure to 17 lbs(on my gauge) cured that and improved the 60 ft. times. My 60 ft. times where not as good as yours are Sometimes when things are really good you got to live with the bad things that come with success