Originally Posted by
Retro Grouch
Where did you get that 1/2 blow off pressure number? I think that it's an "old bike riders fable". Maybe whoever started it is dead now.
1/2 of the tire/rim interface is the rim. For that number to be true there would have to be an industry document somewhere that specified a standard rim for testing tire blow off pressure. I've seen that 1/2 blow off pressure thing bandied about a lot but nobody has ever been able to answer my question about it's origin.
Second hand info from a local bike dealer. He was told this tidbit from one of his product salesman. The manufacturer can't know the vehicle weight of the bike and rider so uses a number that will cover his ass.