I've had several flats on the same wheel (rear wheel only, kinlin xr-300 if that helps), where the hole in the tube is on the section that touches the rim (the inside portion of the rim, the part farthest from the tire).

I can't feel anything through the rim tape (Kore tape), but i've just had my third flat. They're all happening in different places relative to the valve, so I can't figure out what's going on. Should I try different rim tape?

Replace the rim strip. Roger

Replace with Velox rim tape of the correct width to fit your rims.

Does your rim have eyelets? If not, with the rim strip off, check for any tiny burrs around the spoke holes left over from when they were drilled. Run a round file around the rims to smooth off all the spoke holes and follow with fine emery cloth. Then replace with a Velox cloth rim strip. This stopped repetitive punctures we were getting on a new Velocity Deep V rim on the tandem (125 psi.)

Also make sure that you don't have any over-long spokes protruding so far above the nipple heads that they reach the rim strip when it is forced into the spoke hole by the air pressure.

For rims without eyelets, I've built two wheels with the little plastic plugs that Velocity makes for their non-eyeletted rims. They would protect the tube from burrs. But I'm still partial to rim strips, so far.

Make sure that your rim strip completely covers every tiny little arc of spoke hole. If the tiniest little crescent is exposed, when you pump your tire up the air pressure will push the inner tube into that gap and slice it against the spoke hole.

Thanks, i'll give all of the above a try. At first I thought it was a mounting issue after going through 2 tubes (the first one was an old used tube, so I wasn't sure if it was good or not), but then today had a third flat on a ride (after doing 20 miles on the rim yesterday). Velox + file it is