To obtain an exhaust gas purification method for an internal combustion engine for detecting timing at which an inflow NOx amount flowing into an NOx absorption catalyst exceeds an NOx amount processable by the NOx absorption catalyst, and enriches the airfuel ratio to prevent deterioration of the exhaust gas and maintain good fuel consumption. The tread area is reinforced between the toe and heel areas. The lenses may be tinted for use as sunshades or could be also optically enhanced for use as an auxiliary corrective lens.