sentences:  Because of slow air leaks, changes in the weather and ambient temperature or other conditions, tire pressure will occasionally have to be corrected via the valve stem with compressed air which is often available at service stations.Under-inflation of tires can cause premature and uneven tire wear, excess fuel usage, and carries an increased risk of explosive failure (blowout) especially after prolonged high speed operation at high temperatures.Overall, these factors decrease the life of a tire by up to 20%.