Does it make sense to change your car’s tires one at a time? (A vaccine parable)

The Pediatric Insider

© 2014 Roy Benaroch, MD

Ron was puzzled. He had been a mechanic for many years, and had known Ms. McCarthy through two previous vehicles. But what could he say to a request like this?

“I don’t see why you wouldn’t want to do it this way. What’s the harm?” The mother of two seemed sincere and earnest. Ron knew she wanted to take good care of her car, and the kids who rode with her every day.

“It’s just not done this way. You need four new tires, let’s just replace them all at once.” Ron stuck his finger into a well-worn tread, showing his customer how shallow the grooves had become.

“But isn’t that too hard on the car? I mean, that seems like a lot to do, all at once. Let’s space them out, one tire every two weeks. I’ll just come back.”

Ron scratched his head. Cars: that’s what he knew. Light trucks, electrical systems, AC systems too. He had even studied and learned how to fix and maintain foreign cars, and hybrids, and the newer electric cars—more computer than car, really. If it rolled on wheels, Ron knew how to fix it. It was his job.

“No, you see, it’s a safety thing. A tire could blow—see how bare these are? And you won’t get good steering on these, which is also unsafe.” Safety, thought Ron, that will convince her. He took safety very seriously, and imagined that this nice lady with the kids would put safety first. “Besides, cars are designed to have their tires replaced. Tires wear out, so the car was designed to safely go up on this lift so we can replace the tires. No problem!”

“But how do I know it’s safe? I read on the internet that replacing all of the tires at once can stress out the suspension, and lead to premature angulation of the mesmerglobber, and on Oprah I saw this actress and she said three months after she had all four tires replaced, her transmission broke!” Ms. McCarthy started to sob.

“OK, look, it’s ok, look, um…” Ron looked for one of his less-greasy rags to offer as a handkerchief.

“Waiting a few weeks between each tire won’t really hurt, will it?”

“Probably it’ll be OK, I guess. But tires are an important part of your safety system, like good brakes and seat belts and air bags.”

“Oh, I make sure we never wear seat belts! I heard that once a guy was wearing his seat belt, and he went into a lake, and he couldn’t get it off, and he drowned! I’m not wearing anything that isn’t 100% safe!”

Ron felt lost. “Look, nothing’s 100% safe! A seat belt might occasionally make an accident worse, but 99 times out of 100 it’s much better to wear your belt.”

“I can’t risk that 1 out of 100 chance!”

The mechanic tried another avenue. “But it’s the law, you have to wear your seat belt, and your kids need to be in the right kind of car safety seats too.”

Ms. McCarthy’s eyes grew dark. “Yeah, the law. That’s just it—the government is forcing these seat belts and new tires on us, because the government is controlled by the car manufacturers and the insurance industry! If seat belts really saved lives would there have to be a law about it? That’s why I disconnected my front brakes.”


“The front brakes are just a booster anyway. If the brakes work as well as they’re supposed to, why do we need a booster? It’s just more money, it’s all about the money!”

Ron had been fixing cars for years, and he owned his own shop. He made pretty good money, but selling new tires and simple brake maintenance jobs weren’t really profitable.  He did those things to keep cars running well, and to prevent bigger problems later. In fact, if he let more rotors go bad and transmissions fail, he’s probably make even more money from the expensive jobs needed to fix them.

“Tell you what—I’ll fix up your brakes for free, just my cost for parts, OK? Really, it’s not safe for you and the other drivers if you don’t have good brakes and tires.”

“What do you mean, the other drivers? They have their own brakes! That’s exactly what this web site I found was explaining, that you’d come up with all of these dumb reasons to take more of my money and hurt my car! You’re not really interested in keeping my car healthy, are you?”

Are you?

A previous vaccine parable

Why do some parents refuse vaccines?

An illustrated history of one anti-vaccine myth

Too many too soon debunked


Adapted from a post that originally appeared here in June, 2010.

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10 Comments on “Does it make sense to change your car’s tires one at a time? (A vaccine parable)”

  1. nasik Says:

    a moronic analogy for a moronic site – totally void of logic and reason


  2. A bit of a stretch analogy, don’t you think? Replacing 4 exact tires vs 4 different ones?? Try putting 4 different tires on the car and feeling safe then. Choosing not to give multiple vaccinations at the same time is a wise one. If the child has a bad reaction how would you know which vaccine caused it?


  3. Julie Kardos Says:

    Spot on! Dr. Roy has read all of the medical textbooks and continues to read all of the latest research on vaccines and other pediatric information so that non-pediatrician parents don’t have to do this for their children! Vaccines safety is constantly monitored, and fortunately the data show that giving multiple vaccines at the AAP’s recommended schedule is a safe practice. Not vaccinating on time leaves kids vulnerable to preventable diseases that can cause disability and death.


  4. Chip Says:

    Funny post, Roy. I think many won’t get it though. 🙂

    It’s fun when people whose knowledge of science and medicine can be gleaned through a 5-minute Google search tell lifelong medical practitioners that a procedure is unsafe or maybe they should change the way it is done because they feel it is too much for a child’s system. And then they reply with the brilliant retort of “totally devoid of logic and reason” without offering one sliver of either themselves.

    It’s understandable to be scared for your child — vaccines can seem so scary for the under-informed and they make your kid cry and they can be crabby a while after. And yes, like EVERY medical procedure, it cannot ever be said to be 100% safe and nothing will ever happen bad as a result. But the incidence of any reaction beyond the mild to moderate are extremely rare — you’re more likely to get into a serious car accident on the way to the doctor than have any of those effects.


  5. Dr. Roy Says:

    Ms. Ransom makes the argument that giving vaccines separately is a wise choice, because “If the child has a bad reaction how would you know which vaccine caused it?”

    The chance of a “bad reaction” is vanishingly small– very, very close to zero. A child has a higher risk of a serious car accident on the way to the doctor than of having a “bad reaction” to a vaccine. Multiplying trips to the doctor increases that risk, and more importantly increases the risk that the child will remain unprotected against serious illnesses that really do cause bad reactions.

    Also, splitting up vaccines is cruel to the child. Each time a child comes to the doc for shots, it hurts, at least a little. Multiply that more and more times, and you’re not only exposing a child to more pain, but you’re also reinforcing his fear of needles and doctors. It makes our job much more difficult when children are fearful (and, of course, it’s no fun for the child.) Get the vaccines done as efficiently as possible, in as few trips as possible, using safe, proven combos according to the recommended schedule– not some “made up” schedule invented to sell books by preying on fear.


  6. Rachel Says:

    I figure that the more times the kid is in the pediatrician’s office, the more chance she has of contracting some annoying illness from all the sick, snotty, coughing kids there. Plus, as much as I like our pediatrician, we have better things to do with our time than unnecessarily going back and forth to his office for something that can safely be done in one visit. I think I’ll take the one shot and done, thank you!


  7. OMDG Says:

    Dr. Roy, Just be aware that your definition of a “bad reaction” and a parent’s may be very different. After my daughter’s 2 month shots, she cried continuously for hours and ran a low grade fever. I know this seems like a nothing event to you because the kids you see in the hospital are much sicker than this. However even as a person who is almost done with med school and has seen plenty of *actually* sick patients, it was really hard for me to deal with as a new parent. Caring for an inconsolable, uncomfortable baby is really difficult, especially if you have to do it by yourself for 8 hours in a row with no breaks. Even NICU nurses don’t have to do this.

    My daughter has continued to receive her shots on schedule and I would NEVER consider not vaccinating or even delaying shots. However please try to be cognizant of some of the things parents are responding to when they come to your office complaining of “bad reactions,” requesting that vaccines be delayed. I’m not saying you should honor their requests, but in our case, it would have been nice to have at least been warned that this could happen. And, it would have been extra nice if someone had told me the appropriate dose of acetaminophen in advance so I didn’t have to calculate it off of Up To Date myself with a screaming wriggling baby in my arms.


  8. Maureen Goddard Says:

    If you are going to use an analogy, please make it one that is relatable. And please consider being more respectful of a person’s decisions- it reflects poorly on you when you don’t.


  9. cphickie Says:

    As a pediatrician, when I see a parent doing something really stupid like skipping vaccines for their child, I have a hard time not wondering just how many other unnecessary risks you are taking with your child’s health. Dr. Benaroch’s analogy here is very valid–namely well-meaning people doing really stupid things because they are gullible enough to believe all the crap that floats around on the internet. As I read about measles outbreaks in California and Hawaii this week, as well as continuing whooping cough outbreaks all over the US (and the death of an infant last week in California that was too young to receive whooping cough vaccine), I say this to you inane non-vaccinating parents: some of your children are going to be hurt by vaccine-preventable diseases due to your ignorance and arrogance. Yes, you have the right not to vaccinate, but decisions have consequences and the diseases that vaccines prevent don’t care a whit about how otherwise healthy a life you may give your child. Too many parents are not vaccinating there children now in the US and your children no longer have the benefit of the herd immunity they once had from all the other parents who do vaccinate their children. What makes me sad is that children will pay the price for these horrible choices made by their parents. –Chris Hickie, MD, PhD


  10. bye Says:

    …. People like this are actually allowed medical licenses? America is doomed.


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