himespau 

I use cheapie forte tubes (26x1.25 if that matters) and cheapy forte slick tires (metro K) on my do everything commuter/grocery getter/recreation bike (a converted mtb with drop bars and front and rear racks for hauling stuff).

Last night when I went down to the garage (our apartment has an underground garage where we can store our bikes as our apartment is too small) to get the bike to clean the chain and stuff, I found that my rear tire was flat. Pulled the tire off and found a tiny little pinhole (only one) on the inner tube on the outside (essentially right where the tire contacts the road). Since I know where the stem was, I could find the same spot on the tire, and searched around, but couldn't find a hole or something sharp in there, there or anywhere else. I spent maybe 15 minutes looking and feeling around and couldn't find anything, so I just put a new tube in there, and put it back on the bike.

What are the chances there's still something in there that I didn't feel that's going to cause another hole? Is it possible that just the cheap tire/tube combo did it on it's own? I kind of doubt that as it's a pinhole and not right on the seam, not like a wear abrasion. I'm just scratching my head as to what caused it. Could it have been something in there that fell out when I pulled the tube?

I hadn't ridden the bike in a week or 10 days, so it'd probably been flat and sitting on the tire for a while (my bike is quite heavy even before the rack and the wald folding baskets above that rear tire). Could the weight of just sitting on a flat tire have damaged the sidewall? I didn't see any cracks or anything like you would with dryrot, but the rubber there did feel a bit more flexible. No bulges though when I reinflated the tube and put the wheel back on.

Thanks for all your help with all my stupid questions. And yes, I know I need to learn to patch my tires, but one thing at a time.

cycle_maven

It's doubtful that sitting on flat tires for a few days would damage the tires. Also doubtful that it would cause a pinhole in the tube. I've had pinholes caused by "michelin wires"- the stuff steel-belted radials are made of- it frays when somebody drives on bald tires and the tiny wires work themselves into bike tires easily. They're a bear to find- once I flatted three tubes before I finally found it. The best way to find them is to take a ball of cotton and wipe the interior of the tire in both directions- fibers will catch on anything that protrudes. They're almost invisible and sometimes you can't even feel them.

himespau 

Yeah, I doubt the flat caused the pinhole, pretty sure it was the cause of the flat as I could hear air rushing out of it pretty easily when I pumped it up to check. Good call on the wire fray, I might check again with a cotton ball tonight.

FBinNY 

It isn't rare for the cause of a puncture not to still be there later on. Glass tends to stay embedded in tires and make visible cuts in the wall, but small nails, thorns and other hazards often leave no visible mark inside the tire, and can fall or be pulled out while riding.

If you've checked carefully, and didn't see or feel what might have caused the puncture, it's gone and you needn't wouldn't worry about it.

FWIW, I don't eyeball the tire, but run the back of a finger around the inside of the tire. The skin there is thin and sensitive and doesn't miss a thing. And no, it's never come out bleeding, the worst I've had is less than a cat scratch.

himespau 

Ah, back of the finger probably would have been more sensitive than the fingertips that I used.

rep

I use my fingertips, but I have drawn blood! Your hole is very likely from a wire, and they often fall out and are unfindable. I just got a flat from a wire. Went over the inside of the tire carefully several times with my fingertips, but found nothing, so I looked very carefully inside and out. Nothing. Ran my fingers over my Mr Tuffy tire liner and ouch! There was Mr Wire.

bkaapcke

Rub a cotton ball around in there and it will snag on anything sharp. Carry one in your road kit, too. No weight and it works great. bk

nealjoslyn

I have an experience that may applicable here. I once had a series of flats with a certain tire (probably went through 3 tubes, scratching my head). I had run my finger along the inside of the tire each time the flats occured, and I could never find anything. The flats always happened in the same spot in the tube, relative to the tire. So eventually I just pushed really hard in the spot on the tire, and found that there was a thorn which was the exact length of the thickness of my tire, which is why I couldn't find it with my finger. Every time I rode my bike, it poked the tube just enough to puncture it. The tire I was using was also fairly inadequate and was in need of replacement. Anyway, moral of the story is, be extra meticulous when checking your tires for any remnants of debris, etc.