Hi, I wanted to change all belts on my 307...I removed 3 of them, a longer one from the water pump, and 2 shorter ones of the same length (10x910). I didn´t check before if this 2 had almost the same tension. The new belts are 10x915 which should be no problem, but when I give tension to the belts, only the one that is closer to the engine is ok, the "middle" belt is too loose. I wonder if the middle belt normally is the one that also goes over the pulley for the A/C and gets its tension there. On my car, the A/C was removed, so I don´t know if that´s right. Is one belt enough or right for the PS-pump? Or should I buy one with about 900 or 905mm length to get almost the same tension on both belts.