(Jose Soto/The Washington Post)

“Jack, we should call someone. I don’t think he can do this. Do you have reception here? Let’s call someone. He can’t do this.”

That’s my mother-in-law, Maureen. Jack is her husband, and I am “he,” lying underneath a rented Toyota Sequoia on an unpaved road high above Leadville, Colo., trying to solve the SUV’s complex spare-tire retention system so I can change a flat. It is 47 degrees and raining. Cold runnels of dull-orange mud are coursing around me. With Maureen and Jack are my wife, Cathleen, and our two kids Kai and Christina, all huddled around a small pine tree and nearly dwarfed by the pile of luggage we unloaded to access the jack.

Look, I love my in-laws. We get along fine and have, over 15 years, developed what feels like mutual affection and respect. And yet, if that disembodied voice had belonged to my mom or dad, I would have not responded with a chipper “Almost got it!”

Tension with in-laws, especially during the forced togetherness of travel, is rooted in the obvious, says Karl Pillemer, a professor of human development at Cornell University. “They aren’t your family, and you aren’t theirs. And you’re under great pressure if not to like them then at least to get along with them.”

How you handle that pressure can be the difference between having a nice vacation and really needing one.

The author with his wife, kids and in-laws in the Colorado Rockies, hours before a tire blow-out caused a spike in familial tensions. (John Briley/For The Washington Post)

The ground rules: First — and people actually violate this one, shockingly — never invite your parents on a trip without talking to your spouse, says Anne Ziff, a marriage and family therapist who practices in Connecticut and New York City. Second, before agreeing to a trip, make sure people will have their own space and opportunities for enjoyment.

“The point of a vacation is get away from the stresses of life,” Ziff says. “If you really don’t get along, don’t travel together.”

A liberating notion, but because that parachute cord is often out of reach, your next move is to set boundaries.

“Agree with your spouse on when to leave and return, and whether one of you needs time alone during each day,” Ziff says.

Then, it’s up to the blood relative to deliver the message: “Say, ‘Here’s what we’d like to do,’ not ‘Here’s what we’re willing to do,’ ” she advises. “Tone matters.”

The author’s wife, Cathleen Kelly (center), helps their daughter Christina navigate a stream crossing while Cathleen’s father Jack looks on. (John Briley/For The Washington Post)

This can get tricky if, say, the trip is meant to celebrate your in-laws’ 40th anniversary, and they’re paying. In such cases, you may need to be more deferential, and here’s hoping you saved some vacation time for yourself later.

Pillemer adds that for trips involving many people and divergent interests, a resort or a cruise might be “a lot better than everyone being stuck in an isolated beach house for two weeks with only one car.” Settings with service staff can also help alleviate the martyr complex for those who feel that they carry more of the chores load.

Pillemer suggests thinking ahead about how you’ll want to remember the vacation: “Ask yourself, ‘Will I feel better if I go off for the day and do my own thing?’” If the answer is yes, make that happen.

First trip with the in-laws: If I was in charge, this wouldn’t count against your annual leave. But I’m not, so focus instead on what to expect.

“Pre-discuss how your new partner’s family likes to travel,” says Brianna Marshall, a marriage and family therapist in Las Vegas. Some clans play everything by ear, or eat dinner at 10 p.m., or demand your cheery participation in all activities. (Sunrise yogilates!)

“If you’re expecting to relax but their plan is to get everyone up at 5:30 a.m. to be out the door at 6, you need to know that and have mechanisms for managing it,” Marshall says, such as curling into a ball and muttering “There’s no place like home!” until they leave you alone. Okay, she didn’t say that. A better tack might be to acquiesce to their agenda one day but do your own thing the next.

Snipe hunting: If your unease derives from the occasional snipe — say, a mother-in-law telling a grandkid, ‘Don’t you have the BEST daddy in the world?’ with no mention of mommy — just let it go, Marshall says. “Put up an invisible shield, and tell yourself, ‘I’m on a vacation I’m having a good time, and it’s going to be very hard for someone to ruin my mood.’ ”

If the bugaboo is politics or social issues, Pillemer asserts that during travel there “can and should be a demilitarized zone,” and that vacations are not for mining known areas of conflict. In the incredibly likely event someone breaks that rule, he adds, “remind yourself it’s a limited amount of time” that you have to spend with these people.

Also, if you’re expecting to be provoked, Pillemer advises interior rehearsal, where you run through the difficult interaction in your mind and practice a defusing response. That way, when your sister-in-law mentions that your carefully chosen dinner outfit makes you look like a rodeo clown, you won’t unleash a fury of biting insults — or that, if you do, you’ll nail your delivery. (Sigh . . . okay, he didn’t say that last bit either.)

Get along with one but not the other: Oh boy, this’ll be fun. Team up with your ally and battle your foe to the death!

Definitely don’t do that.

“Play the hand you’re dealt,” Marshall says. “Go along with the one who likes you and don’t worry about the other. You don’t need their approval — you have your spouse. Just make sure that if there’s any negativity it’s not coming from you.”

If you really want to seek higher ground, Ziff suggests the fraught territory of a heart-to-heart talk.

“Find time to say, ‘I really love your daughter, and I know you do too. I also know you and I don’t have a very warm relationship. I’d like your help to make that better.’ It’s very valuable to show that you’re receptive to help. You’re trying to create common ground,” Ziff says.

Full disclosure: This angle could elevate your vacation to a height of Zen or fast-track you to a nearby motel.

If you finally lose it: Don’t hold back, surface every hurt you’ve carried around for 25 years and, pleasepleaseplease post a video of this tantrum on social media.

Actually, no. Our triad of experts all agree that issues will arise on most trips with in-laws — midnight ukulele practice, the mandatory pre-dinner seance, binge drinking — and when you’re seriously careening off your axis it’s best to work through someone the offender trusts to get your message across. If you happen to be the offender, try to receive such overtures with grace, especially if they’re coming from the police.

“Very rarely does open confrontation work,” Pillemer says. He also cites studies showing that negative events have a much greater impact on mood than do positive ones — by a factor of 20 to 1.

“That means that if everything has been great up to a point and then there’s just one blowup, everyone will remember that incident. Therefore, ask yourself, ‘Is it worth it to challenge grandpa on his stance on abortion or the death penalty on this trip?’ People aren’t going to change, and you’re certainly not going to be able to change them,” Pillemer says.

So be a good person, refrain from even thinking “I told you so” after changing the tire, and let the little things — and even a few big ones — slide. You’ll be a happier traveler for it.

Briley is a writer based in Takoma Park. His website is Johnbriley.com

More from Travel:

I could handle childbirth. Could I handle flying with a baby?

How solo travel forced me to become comfortable with being uncomfortable

Champagne, duvets and a 180-degree seat: A frugal traveler’s introduction to first class