I think 30 seconds is a bit too short of a hot timer before the tank kills itself. I've seen people roll their tanks and I try to help them out, but I either can't manage to roll them completely back again, or I don't get there in time before the timer hits 0 and the tank just auto-explodes. I understand that when a tank is upside down the turret mechanisms are getting wrecked and the engine stalls as the oil is seeping into the cylinders... so it could be a technically inspired timer, but that shouldn't be a priority in light of WoT's current balancing.
Tank turrets are only held on by gravity, since they were never designed to go sideways or inverted. Also, the suspension was never designed to take the weight of the tank on a 45 degree angle, which it must pass through in order to be flipped sideways. I don't think a tank would function at all if it were flipped sideways and then flipped down onto its tracks again.