Two techniques of measuring tomato (Lycopersicon esculentum Mill. cv. New Yorker) skin strength under tension were compared. An evaluation of the standard grip technique and a new loop technique indicated that the latter showed a lower coefficient of variation for load/width, stress, and strain measured under tension. The loop technique was used to measure the effect of potassium (K) and calcium (Ca) fertilization on the skin strength of tomato fruit. Recommended levels of K and Ca resulted in the greatest skin strength, while doubling K and Ca levels, or doubling K while applying no Ca, gave rise to weaker skin. The loop technique also allowed for the determination of parameters for tensile relaxation with the Maxwell model being used to describe the viscoelastic behavior of tomato skin.