Well the last of the 4 Sigma Regent 205-65-15 (35 psi) expired. Driving 65 mph it went from minor vibration to major in about 5 miles, then smack (tread slapping on pavement). The tread separated about 1/3 of the way around the tire. Guess the tires can't take 95 degree heat AND high speeds - 70 mph!