Abstract: A sealing ring of relatively large diameter made from an elastomer material, particularly for fitting into a gastight valve is presented for the purpose of preventing and/or alleviating stresses that cause tearings in and on the surface of the sealing ring. This is accomplished by modifying the cross-section of the sealing ring relative to the cross-section of a receiving channel such that the cross-section of the sealing ring forms a central foot which lies in bearing contact with a base surface of the receiving channel and is radially limited by two concave indentations. The two concave indentations are dimensioned so they form, with the corresponding boundary surfaces of the channel, a respective cavity, into which a substantial part of the elastomer material can yield whenever a surface load is applied to the exposed sealing surface without substantially altering the concave configuration of the indentations.