When to change rear shocks

I have a 2011 Double Cab 4WD TRD SR5 i bought with 62K miles. The rrear shocks seem fine but seem to sag quite a bit when I loaded my 400lb motorcycle in the bed. How would I know when I need to change the rear shocks.

 

It's the rear leaf springs that are crap. They were not ment to carry a load. Might have to get an add a leaf to help support the laid you're carrying

 

X2

 

x3, shocks are there to maintain tire contact with road. Springs support weight of truck and contents. Gas pressure shocks last quite a while compared to older styles. Rears last longer than fronts. In the old days on a 4x4 I would replace at about 50. As with other things it depends on how you use truck and roads you drive. Lots of driving on washboard roads will shorten life.

 

Ride Rite Air Springs (Bags) will fix it. I had them on my '05 with the crapo rear springs... and my 2010 was fine until recently and now I am feeling bumps I did not before (63,000 miles)... Will put the Ride Rites on my 2010. Upgrading the rear shocks to Bilstein 5100s also may be in the works.

 

Yup. Firestone ride rite airbags are what I needed on my last rig. Needed to support over 400 lbs daily for work hauling stones etc for a landscaping job. I combo'd with bilstein 5100, which also leveled and added 2", and the 400 lbs load felt like a pile of feathers. Plus the air bags and 5100's are adjustable depending on load which is super sweet.