Last week i was riding on the gravel roads about 4 miles from home and got a flat (no spare). While waiting for the wife and kids to pick me up i took the tire and tube apart. I noticed the hole/tear in the tube was at the base of the valve. What causes this and i'm guessing it's the weak point of the tube? Anything i can do to prevent this in the future? Thank you all and have a HAPPY and SAFE JULY 4!!!