I have a sorta light weight 54cm fixed gear (18 pounds) and I weigh about 115 pounds. I have a set of continental ultra tires for my 622/14mm (700x23) bianchi rims with standard 20-25 tubes. The thing is, i absolutely hate when my tires are soft or under inflated, but i dont want to ever over inflate my wheels and accidentally pop a tube. What can i do for the highest possible tire pressure yet prevent over inflation.
As I've said in other answers, the right tire pressure function of you and your bike and your terrain. You'll have to play with the tire pressure to balance the ride quality.Just because the tire says pressure x on the sidewall doesn't mean it makes any sense running the tire at that pressure since it might just give a bouncy ride which compromises your control.
That being said, your body will probably give out due to discomfort before you ride at the highest possible pressure the tube takes before bursting provided there is no damage.
For a properly inflated tire, see (1) in the first image from Schwalbe:
(2) is what an underinflated tire is like.
I have no doubt the Continental Ultra Sport tires can run at least 115 psi (I have run similar continental tires at pressures more than 120 psi, and I am significantly heavier than 115 pounds). However, the ride quality suffers, the tires become bouncy and so on. For someone at 115 pounds though, the "optimal" tire pressure will be significantly lower than 120 psi. Of course, experiment with pressures at your own risk -- the minimum and maximum tire pressures are what the legal department at the tire manufacturer thinks you can do, so it would be wise to head them.
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The rule for the right pressure for a 700x23 size is 80-100 psi for a person weighing 60-75 KGS and 100 -130 psi for a person weighing above 75. Please check your max tire pressure on the tire and fix up with a tire pressure as mentioned above. P.S: Also make sure the tube is in the right position between the rims.. Else you might end up with a snake bite flat.! Hope you enjoy the ride:)