How can I tell if I need a REAR wheel alignment?

I have a front-wheel drive Ford Fusion. Obviously you can tell if you need a front-wheel alignment by seeing if the car drifts straight or not, or if your steering wheel tilts, or by uneven tread wear. But how do I tell if I need a REAR-wheel alignment?

(Yes I capitalize "rear" because so many people answer this question without paying attention)

I don't know if there's a real indicator that you need a rear wheel alignment, unless you see that your rear tires are wearing very unevenly, or perhaps you hit a curb really hard with your rear tires. If you're buying new tires, it's a good idea to get a wheel alignment on all four tires, since many of today's cars require all four get an alignment. Your alignment should be checked at least annually, to make sure you're not wearing out your tires unevenly.

No way to know without having it on a 4 wheel laser alignment machine. Are you sure that the rear wheel alignment is even adjustable as on most cars it is not.

The only way you can really tell is to have a four-wheel alignment done at a shop that has the proper equipment to do it.

Uneven tire wear is the indicator for rear alignment.

Hey Buddy… When ever doing an alignment on FWD or AWD vehicles the rear alignment has to be set first before doing the front.
Go to a different alignment shop if they don't tell you that.
Rear wheels out of alignment can cause bad tracking, tire wear, and if the toe adjustment is off make the car feel like the back tires are not gripping the road.
Always do a 4 wheel alignment even if you don't have any symptoms. Just doing the front is useless.

I don't know tbh

Rear wheels rarely need adjustment. I have seen cars that obviously must have been wrecked that when driving down the road seem to go a little sideways. If your car has been in a serious accident, you should try to see with friends, or mechanic, if your car needs this kind of adjustment.

Otherwise, I have never heard of such a need.
Since your car is front wheel drive, any accident to the rear could have pushed one of the rear wheels off alignment. That is what you need to check.

You go to the center part of the frame or crossmember at front of vehicle. Make a v out of a long string there. Go to the same spot on both sides rear axles. Is one side on string shorter or longer than other? Is there uneven tire wear. If in a developed Country they will have a shop that can do this.