One of the things I have found that affects Tyre tightness in fitting is The Rim Tape, I prefer to use Velo tape that is nice and thick, but this fills in the recess where I would normally put the bead of the tyre to give me a bit of slack. On the Mountain tyres- I am generraly OK but these Slick Things that I fit occasionally are very tight. I have a set of wheels that I fit the Slicks to and this set have a neoprene rim tape. Very thin but still strong enough at 100 psi to stop any problems.
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How long was I in the army? Five foot seven.
Spike Milligan