synthetic

My girlfriend has a diamond back insight 1 hybrid, and one day we noticed her tire get flat, We pumped it up continued the trip, when we finish flat again. So I changed the tired... and it occurrs again, I have gone through 5 tires, and apparently what happens, after the night passes the tire is flat in the morning, but a quick pump up fixes it for the day. What should i look for as the cause of the problem? Im kind of afraid to tighten the presta valve too much as i broke some on 2 tires changes before, right after putting them on!!

we live in san diego so i dont think cold air is the problem, at that both tires would deflate..

FR4NCH1SE

You say you replaced the tire, but what about the tube? It doesn't matter if you replace the tire if the tube has a puncture in it, you can pump all you want but your tire will still be flat.

I blew out my tire yesterday, I had to replace the tube because when I hit a curb apparently it punctured the tube and a nice 3 mm hole was noticeable. I don't have a patch kit and a new tube only cost me 4 bucks so I just replaced the tube. And did all the other work and my ride is back on attack.

synthetic

sorry, i meant the tube. I have not yet replaced the actual tire.

10 Wheels

Each time you have a flat and remove the tube, you need to pump it up and find the leak.
Then match the tube to the tire and look for wires, glass, etc.
Always place the logo on the tire centered on the valve hole on the rim, that will give you a reference point too help fine the problem.

Homebrew01

You may have a sharp object that is stuck in the tire, so it puts a small hole in each new tube. Check the tire carefully inside and out.
Most tubes lose a bit of air gradually, but not much in just 1 day.

You can patch the tubes. Buy a patch kit or 2 from the bike shop. Put a little air in them, then fill a pot or sink with water & look for the bubbles. Dry it well & follow the patch instructions.

Most people have good tubes with them when they ride for on-the-road flats, and then patch later when they get home.

synthetic

should i buy tire foam to solve this problem? will it work with a presta valce bike?

10 Wheels

Just learn how to patch the leaks in the tubes.
Carry a spare tube or two when you ride.

StanSeven

I wouldn't use that. The best thing to do is find out what's causing the flat per 10 wheels post (number 4 above). Then just put a new tube in or patch the old one.

DannoXYZ 

No, there's a bike-specific product called Slime that you can squeeze into the tube. The bottle fits best into a schraeder valve with core removed. If you've got presta-tube with removeable valve-core, you can take it out and screw on a schraeder adapter and squeeze the slime in. Otherwise, it's really hard to get it past the presta-valve. You can buy tubes pre-filled with Slime. Then add Mr Tuffy tyre-liners and get kevlar-belted touring tyres.

But before doing ANYTHING, find out what caused the flat in the first place. Pump the old tube a couple of pumps so it's a little larger than the tyre and feel around it for the hole. Then line up the tube next to the wheel with the valve next to the hole in the rim and inspect the tyre and rim around the spot where the tube is leaking. There's two ways to line up the leak so flip the tube over 180-degrees and inspect the other side of the wheel as well. If the leak is on the inside radius of the tube, then you've got a sharp burr on the rim or the rim-strip has slipped sideways. Replace ALL rubber rim-strips with Velox tape. if the hole is on the outer surface of the tube, then something has poked through the tyre. Remove the offending object from the tyre before replacing the tube. Sometimes, the tyre can have a cut from sharp rocks, potholes or glass. This lets the tube squeeze out and pop. Most likely not in your case since it's a slow leak.

So yea, stop replacing tubes over and over. Fine what's causing the flat first.

synthetic

solid advice, thanks.

DieselDan

Inflate the bad tube outside the tire. If the puncture is on the outside, look for something embbed in the tire. If the puncture is on the inside, then you have a bad or misaligned rim strip.