My truck's right front tire has a worn ring around the inside, the rest of the tire tread is good. The left front tire is also good all the way across.

Would this be caused by worn RH side ball joints?

 

Yes could be ball joint. I had the same issue on my F250 and it turned out the lower ball joint was rattling around.

 

Thanks Heli for your reply.

I tried rocking the wheel top & bottom while it was jacked off the ground. I couldn't get any movement.

When ball joints are replaced, is it best to replace both the upper and lower?

 

Most go ahead and change both beings you are right there.Just makes sense.A good front end alighnment shop can steer you in the right direction if they are honest on that inner wear.

 

Not that this is a fail safe check but....I know when I replaced my pass side the original ones from the factory did not have zerk fittings. If you check and do not see grease fittings and have high mileage it might make sense to replace due to age even if you dont see any movement. Being able to grease them will obviously extend life.

 

Are the OEM replacement ball joints fitted with zerks/grease nipples?

 

I think Moog has grease zerts but several including me have bought the XRF ball joints and they have zerts.