Yes your tyre can split like that. Sometimes there are faults in them. You might have rolled over something sharp.

You can also get splits when tyres get really cold, then really hot. Rubber is a bunch of long chain molecules!

You may have hit a rock or pothole earlier which broke the reinforcing belts, leaving a small carbuncle which went unnoticed at the time. This then bursts later at its leisure. The straight hole would suggest a creasing of the belts in that area at some time.

If that's the inside wall, it wouldn't be noticeable at the time without jacking the thing up and carefully inspecting the inner wall for damage while rotating the wheel. The only other indicator might be a bit of vibration, but there could easily be none.

Thing is this is the third time this has happened, in a 12 month period. The first time was last christmas, on a motorway in germany, and the second time was on a country road, and the third time was on a country road as well.

Here's a pic of the second tyre, can't find the first tyre at the moment : www.freeimagehosting.net/mhuwb

I don't know what I'm doing wrong.