You don't have to worry about being stopped for expired inspection in another state. Make an appointment for an inspection as soon as you get back. If you get pulled over when back in PA, tell them you have been out of state and you have an inspection within the next few days at X garage. Chances are, they'll let you go with a warning or ask you to send in proof of inspection.

Get it done ASAP when you get back...

It may depend on the state. I lived in TX for 4 years while in the Army with my vehicle registered in PA, and had an expired inspection sticker pretty much the entire time.

Get it inspected on your return to PA.

PA inspection stickers are of no concern to cops in other States other than to give them a purported cause for a pretextual stop.

If you are excessively concerned over it, then time to your return to coincide with the nearest inspection place upon crossing the State line, where you have your vehicle booked in for inspection.

I don't think it was required at all for active duty out of state, and only PA would enforce it if you had the vehicle back home.

I think my stickers were still valid when I was in SC and NY states but they definitely expired at some point when I was in CA and WA.. was never an issue.

I’m an inspector.

You have 10 days after you return to Pennsylvania to get your vehicle inspected. Be prepared to prove it hasn’t been 10 days yet if you get stopped.

Good answers!

It's worth noting, you can get an inspection sticker 2 months early. If it's due in April, you can get it inspected in February, and get April stickers. Make it clear to the mechanic If you want to do that though, they often will put on the earlier month if you aren't very, very clear.

Agreed. I've been through something similar a couple times before. I recommend calling to make the appointment before OP gets back, and ask the place to send a confirmation via email.
They'll tell you that it still may not stop you from getting a ticket, but if you get them to send that to you, then the officer who pulls you over may be nice about it and let you off with a warning.

On a similar note, I had a dead headlight and the officer that nabbed me was super chill about it. It was Tuesday and I told him my boyfriend at the time was going to help me with it on Thursday (which was all true, if that matters to anyone here.) Instead of fining me and calling it a day, he gave me a written warning that required me to show up at X-location in something like 7 days to prove I had gotten it fixed.

Planning ahead seems to greatly help with making the punishment lighter.

Out of state cops don’t care about your PA inspection stickers. They are almost certainly not going to give you a ticket over it.

Not advocating this, but I once drove a car for two years with expired stickers, including to the other side of the country and back. Never got stopped once. Now definitely don’t do that, but I also wouldn’t put too much worry into it. Just get it done when you back.

No worries, as long as your insurance is good. When you are in a different state you fall within a grey area where unless the PA DMV puts out a national bulletin against your license you are good to go until you return to registered state. Upon return, you have 10 days in PA to get it inspected. If you are pulled over during that time, be super cool, super respectful and tell all the facts like they are. If you do that, no cop is going to give you a ticket. A trooper might give you a written notice where you are essentially “on notice” with the state to show out and provide proof you are taking care of it or face the full consequences. Otherwise though, as long as you actually do it and not wait a couple months once you are back, you are good.