Originally Posted by
CliffordK
For butytl tubes, I've found that the larger the tube, the slower the leak.
So, find the biggest tube that will fit in your tire.
My belief is that if you have a small tube in a larger tire, inflation will tend to stretch the hole open.
It also allows more air to pass through the tube and bleed out even where there is no hole. OTOH, if you run higher volume tires and lower pressures the whole pressure bleeding off thing is minimized.
You are correct if air bleeding off and having to top off is the major factor for you. I do the opposite of what you suggest for more than one reason that for me trump any hassle of topping off..
The first is you save a little weight in a key place. If you are carrying a few spare tubes the weight adds up, but at least the spare tubes are not rotating mass. If you go for heavy duty (I go for light one) they are heavier, thornproof even more so (they weigh a ton)
The next is bulk of the spares. In larger sizes 2-3 spares are a pretty large bundle. If you go for heavy duty (I go for light one) they are bulkier, thornproof even more so (they are huge)
Then there is the suppleness of the ride. Having a stretched out tube gives a ride closer to not having a tube. It is a little more like a tubless tire with a flexible sidewall. Some riders apparently don't notice the difference, or don't care about it, or maybe even don't even like the feeling of a flexible sidewall. To me it is something that I value. The more heavy duty tube the less supple the ride as well.
Oh, and the tires are a little easier to mount without pinching a tube with an undersized tube.
All that for the cost of having to top off more often is a good deal in my mind.