no, just replace the side thats bad.
yes you should replace both sides at the same time
Turn your wheel all the way to one side.You will see the rubber boot if this is cracked replace that side.Yes,it is valuable to check both sides at the same time,but it is not necessary to do both at the same time.
Sure, they were both installed at the same time and they both burned for the same length of time. That is the reason that you want to replace lights in pairs...it is just a matter of time before the second one burns out.
No they don't go bad at same time but any smart technician will replace both at same time.
Yes.
Yes, you can replace the rims and tires at different times, on both cars and motorcycles. However with cars it is usually recommended to replace them both at the same time, since it is much easier and the rims get wear as well.
No, you should have one replaced at a time, and do the second only after the first heals.
No, unless they are over 5 years old. In that case I would replace them at the same time. Otherwise just replace the defective battery.
Always replace inner and outer wheel bearings on the same wheel at the same. You don't necessarily have to replace the bearings in both wheels at the same time, though it's not a bad idea, but always inner and outer on the same wheel at the same time.
Not unless they are all worn out. You can replace just two tires. I recommend you replace both front or both rear tires at the same time. Also make sure that all 4 tires are the exact same size. If the tires are fairly new and not worn you can replace just one tire if one was damaged as long as the size is the same.
They both contract at the same time.
Since it's the lower, I think you can replace just the ball joint. Most of the time the uppers are replaced by replacing the entire arm.