Wow, dyna beads and Firestones and all in the same thread....
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Those Firestones are made for looks only, they are not a great tyre and track poorly, could just be your tyre mate, the tread pattern lends them to follow any lines on the road and track poorly . It is possible its out of balance but its performance will never be as good as a "proper" tyre. If you like your bike to handle well, look for better tyres..... BT45's are very popular here.
As far as i am concerned, Dyna beads are a load of rubbish, they aren't recommended for high speed or low lean angles {this is from the PDF on their own site}, so i would never fit them to anything i own......{grabs popcorn and sits back}
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26psi.? Is that what the manufacturer recommends.? Try running 30-32 psi and see if that makes a difference....