With tires youre not going to be able to see defects.
2 correspondents mentioned using tubes in auto tires. @asemaster did it for his job; @Beancounter did it for his wire wheels.
Relatively impermeable doesn’t mean impermeable. If it were truly impermeable thickness wouldn’t matter. The number I got from an NBS paper puts it at 1.88×10-11 in units of meters, atmospheres, and seconds.
I just calculated how much air my bicycle’s tubes (700×28, inflated to 100 psi) should lose to permeation, get 2.5 psi/day. That’s about what I see. If you have wider tires (smaller area/volume), lower pressure, and thicker tubes you can get it down to .25. You won’t see permeation bubble.
You are not going to get a specific answer because there is a wide variation in how fast tubes loose air, as well as a wide variation with tubeless tires loosing air.
For example, I have a couple of hose reel carts with small tube tires and every time I go to move them, at least one tire is completely flat. I have a rolling garden seat with pneumatic tires, don’t know if tube or tubeless because they have never lost air. They do have valve stems though so they are not solid.
I have an old riding mower that I bought in 1997. I don’t use it as a mower any more but I do use it to haul my utility trailer around the yard. The front tire had so many plugs in them that I had to air them up every time I used it, this was a few years ago when I was still using it as a mower so I used it weekly. I got tired of that so I put in tubes and haven’t added any air since. Don’t know if they have the full pressure but they look full so I leave them alone.
Well let’s be clear. That was for a 60 year old car, running bias-ply tires on true spoke wire wheels that had not been sealed to accept tubeless tires. Out of a crew of 7, I was the only one who had experience with tube type tires.
Radial passenger tires are not compatible with tubes because the constant flex of the sidewalls creates friction and heat rubbing against the tube.
So putting aside vintage/classic cars with custom wheels, it’s safe to say that automotive tires do not use tubes.
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Mine are 700 x 32, inflated to 50 psi, maybe explains the x10 difference in air pressure loss rate. I’m sort of surprised a 700 x 28 bicycle tire would be normally expected to lose 2.5 psi per day. Seems more than most owners would put up with. Maybe I should just enjoy my good fortune, think of it as embarrassment of riches, and stop asking too many questions …lol …
Those 2 cut it down to .5 psi/day. Are they thicker tubes?
I’m surprised you ride on 50 psi tubes, putting twice the rubber on the pavement. I calculated that a 26×2.125 tube inflated to 60 psi would lose .25/day, figured that’s what you have.
I asked in a bicycle forum; everybody thought this was standard loss. Some begin their rides by adding a few pounds. I don’t mind riding at 90 or 80 myself, so usually only pump weekly.
Around-town non-suspended pandemic cruiser, so reduced tire pressure necessary for ride quality. 700-series x 1.75. One loses air faster than the other, which is the one with a new Specialized tube. I expect the new tube is a performance-design so a little thinner. I’ve never owned a road bicycle w/skinny tires, so didn’t realize pumping tires frequently is expected.
When you fill a tire from zero to 30 psi, some heat is produced. Can be that yust after filling temperature in tire is 110 degr F.
Then next morning at 70 degr F it has cooled down, and pressure lower.
So if you then fill the 3 psi extra, and check next morning, it will not have lost that much pressure, mayby only 0.5 psi.
Filled in my made pressure/temperature calculator with begin situation 30 psi at 105 degr F temperature of gascompound in tire.
Then Going down to 70 degr F next morning, it gave 27.23 psi if totally dry gascompound in tire (Nitrogen filling aproaches that) , and 26.59 psi if enaugh water in tire, like filling with normal air, with all the humidity in it.
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Yep. A pain to stretch these to get onto rim, but no more pumping!
Garden cart, later wheelbarrow, even later hand truck.
Pumpless…
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Yep, I am a bit of an obsessive about tire pressure. Have 2 cars, 8 tires (not counting spares) check them every two weeks, cold, as in not run for 8+ hours.
Rare if none of them need air. More likely 2 or 3 will. If it has been a “rough” 2 weeks --rural roads, longer distances, then maybe 4 or 5 will need air.
Usually need 1-4 lbs of air each, always aim for a bit over the “doorpost’s” ratings.
Need to stay alert for changes in weather. Not yet cold here in Maine, went from 70s in past several weeks to 50s. When the highs are in the 40s, and low in the 20s will definitely be checking more often. Reverse pattern true in the springtime, obviously.
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