I had broken springs on the rear axle last Oct. and replaced all 4 with the OEM spec rated springs; mine are 3,500 lbs axles. Got home OK but upon inspection this spring, I noted that the replacements had almost no arch in them. My conclusion after replacing them with heavier rated springs was that the springs did not live up to their rating? Chinese? I don't know. My trailer gross is 7,850 lbs and axle load at the scale was only 5,700 so the springs are not overloaded. I would not run the axles with different springs.