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Typically if it was a bad CV joint you'd hear a clicking noise when your turn the wheel. The only way to get an idea of if it's stuffed without pulling everything apart is to get under the car and see if one of the CV boots is split. CV joints are designed to last a long time but depending on the amount of miles the car has travelled, they can fail without any indication such as a split boot etc. So if you hear the clicking noise when turning despite not having a torn boot, then that will more than likely be the culprit.
Other possible causes could be a bent rim, out of round rim or tire, bad tie-rod ends, bent driveshaft, improper tire pressures, uneven tire wear etc.
Your best bet would be to take it to a reputable tire shop and let them diagnose the problem, or even just to get a bit of expert advice. It's good that you've eliminated some of the possible causes such as unbalanced wheels and defective balljoints as that will save a lot of mucking around. Best of luck with getting it sorted, fingers crossed it turns out to be something simple.
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