When comparing one tire to another, you can use the tuning fork effect to approximate pressure. Just flick the known tire with you finger and listen to the "tone". Inflate the other tire to match. Differences between tubes, rims , hubs, and spoke gauges and counts can screw this up but not by too much.
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Robert
No matter where I go, here I am...
Last edited by rpenmanparker; 07-02-14 at 03:00 PM.