You would need new shocks and struts and quick strut if you are currently experiencing one or more of the indications to follow. Worn out, damaged, or leaking. Leaking is the easiest to determine, this is by basically checking for decrease in the fluid level in the reservoir. If the reservoir is not full, look for oil, or wetness on the shocks and struts. While you are at it, check for apparent broken mounts, and dented housing.
If you are not experiencing any of the indications, and did not see any visual leaking signs, however, still unsatisfied with the handling of your car when towing a trailer, or hauling an overload, you may want to consider upgrading the original factory strut assembly. The upgrade would provide you with improved handling, and a smother drive, given that the new shocks are stronger, and stiffer.
Most people choose to replace the factory complete strut assembly on older cars to strictly improve the overall quality of the drive. This eliminates the bouncing and rocking on rough roads. Furthermore, you may decide to upgrade your struts if you are interested in performance handling. This is archived by upgrading to gas charged shocks and struts. This type is charged with high pressure of nitrogen gas, which minimizes the hydraulic fluid foaming inside the shocks. This essentially reduces fading on rough roads, and assists in maintaining control at sharp turns.
Moreover, there is shock absorber that fall into a different category. This provides an increased control and improved resistance. Heavy duty shocks and struts are considered by experts to be too harsh for everyday driving. Last but not least, the air-assisted shocks. You would want to consider this type if you are constantly towing a trailer, or hauling extra cargo. It is also known as the overload, surrounded by a coil spring to help increase the loading capacity of the suspension. It may be useful to mention that the overload type dedicates a stiffer ride than the standard shocks, however, is equipped with an adjustable air bladder to assist in carrying extra weight.