I recently replaced my rear wheel/rim on my mountain bike, and in the last couple weeks I've gone through, like, 8 tubes. I can't seem to get one to hold air for more than a day or so.
More details: this is a pretty standard 26" rim. I've repeatedly checked the tire and the rim for anything that could be causing this, but there are no thorns, spokes, sharp edges, or anything like that. I'm very careful when putting in a new tube not to pinch it in between the tire and the rim.
When I put in a new tube, I inflate it enough that it won't get pinched, carefully get the tire back on the bead, and then inflate to max pressure, deflate to below min pressure, and then re-inflate to mid-pressure.
The tube then usually lasts me through one direction of my 8-mile commute if I'm lucky. On inspection, there is usually a gash between 1 cm and 1 inch long running lengthwise on the side of the tube that was facing the rim.
This never used to happen to me with the old rim, but unfortunately that one was banged up enough that it couldn't be properly trued anymore. I've tried every permutation of slime and tire liners, and I'm getting very frustrated. Can anybody offer any suggestions? Thanks in advance.