It’s that time of year again, when the weather is cooling down and yellow warning lights that look like baseball bats dropped in punchbowls start appearing on dashboards. Yep, a gas’s pressure drops as temperature drops, so your tires might be a little bit low on pressure, not enough to tell at a glance but potentially enough to set off your tire pressure monitoring system warning light. No big deal, because even if you don’t know what pressures your tires should be running, finding those few numbers should take less than a minute. This is gonna be a super simple story, but sometimes simple can be helpful.
You won’t find this information on the sidewall of a tire because sidewalls display the maximum pressure of the tire, not the recommended tire pressures from the car’s manufacturer. Inflating tires to the maximum pressure they can hold may have undesirable effects on a vehicle’s handling. Overinflation can reduce a tire’s contact patch and therefore its grip on the road, and running the same pressure in all four tires on a vehicle calling for staggered tire pressures may change the handling balance of the car.
Instead, you’ll find your tire pressure on a placard inside your vehicle, usually in the driver’s door jamb. In fact, it’s a federally mandated legal requirement, as FMVSS 110 section 4.3 states:
Each vehicle, except for a trailer or incomplete vehicle, shall show the information specified in S4.3 (a) through (g), and may show, at the manufacturer’s option, the information specified in S4.3 (h) and (i), on a placard permanently affixed to the driver’s side B-pillar. In each vehicle without a driver’s side B-pillar and with two doors on the driver’s side of the vehicle opening in opposite directions, the placard shall be affixed on the forward edge of the rear side door. If the above locations do not permit the affixing of a placard that is legible, visible and prominent, the placard shall be permanently affixed to the rear edge of the driver’s side door. If this location does not permit the affixing of a placard that is legible, visible and prominent, the placard shall be affixed to the inward facing surface of the vehicle next to the driver’s seating position.
Indeed, if you look in the driver’s door jamb, you’ll see a sticker that looks like this. Simply find the tire size your vehicle is using — for example, 205/50R17 — grab the recommended pressure off that line, and now you know what your manufacturer’s recommended tire pressure actually is.
Some European cars, like my 2006 BMW 325i, have more complex tire pressure labels, but they’re more complex for a reason. See, tire pressures are often a tradeoff between load capacity, comfort, and high-speed stability, so some automakers give you a choice of pressures depending on what you’re carrying in your vehicle. If you’re frequently running at racetrack speeds or carrying a full load of passengers and luggage, use the higher set of pressures for your tires. Otherwise, stick to standard.
Remember to set tire pressures cold, meaning before you’ve driven your vehicle any meaningful distance. Oh, and if you have a vehicle with tire pressure monitoring, you may have to manually reset the tire pressure monitoring warning lamp using the procedure in your owner’s manual. Once that’s done, not only should you get better fuel mileage, you’ll also benefit from better handling, more even tire wear, and reduced risk of tire failure compared to underinflated tires. So, now that you know, go forth and set your pressures properly. Chances are, you’ll be glad you did.
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When I put the new shoes on my FJ, I did the chalk test and found out it liked 34 PSI instead of the 32 psi it had on the door jamb.
As an autocrosser, the last thing we recommend is to look at what the manufacturer suggests for handling and tire wear.
This is all very “tiring”…ha ha
I would be thrilled if my wagon would tell me which tire needs air when the TPS light goes on. It always seems to be the last tire I check!
Some older motorcycles need higher pressures on modern tyres than they did on the old bias plys. My airhead called for 26 psi front/29 psi rear, but it’s generally recommended to go 6 psi higher for both.
I also tend to check mine when it’s overcast or after the sun’s gone down to prevent artificially high readings on one side of the car as a result of being directly in the blazing sun. I’ve found many times if I did set my pressures mid-day in the summer, that later on the side that was in the sun is now lower then the other as a result of cooling more.
I used to have this argument with the quick oil change guys all the time. My Tracker wanted 25psi and they’d always put in 35psi. It was like trying to guide a pingpong ball down the interstate, it got so bouncy.
When I got my classic Beetle, it felt very “heavy” from the front. When I discovered the sticker for the tires (weeks later) that called 19 PSI for the front tires, I was amazed to see such a low number.
The car had 30 PSI all around, adjusted and wow, what a change on the way the car drove.
Or you can read the car manual…
No one reads the manual but you and me.
But why take the time to open up the manual, look up where the tire pressure specs are, and then find that page in the manual, when there’s a thing right inside the driver’s door that tells you what you need to know?
Unless you mean instead of reading this article, but it’s a little late for that.
Reminds me it would be a great idea to include a small plaque or include the oil quantity needed on the oil cap. That’s the most frequent time I find myself 2x the man-u-el 🙂
I use a paint marker to write the filter # and oil quantity on the radiator crossmember.
-an old wrencher I greatly respected wrote timing info, dates, even specific starting tips on the underside of the hoods of his many 56 Ford trucks. Helped us immensely getting them running for auction after he passed. Thanks, Jim
Good ideas Tossabl
Had the TPS light pop on last week in the work van. As it weighs ~8500 lbs, and was lifted by Quigley to become 4wd, I get rather concerned if all four feet aren’t planted firmly.
Given that I burnt out a Campbell Hausfield mini compressor out a couple years ago(rear tires take 80psi), I went and bought fittings so I can fill the tires from nitrogen tanks I carry anyway. Gonna fill my car’s tires too—just because I can
I use an 80% nitrogen mix.
Me too, straight from atmosphere so it’s organic nitrogen. Sometimes I’ll even go with the artisanal nitrogen at the tire store. Nothing but the best for my car!
So…I get the joke, but you guys know there’s a difference right? Just like the properties of steel can be changed with a small percentage of alloy…
I know that in F1 the inconsistency of using air in the tyres would lead to measurable differences on handling and lap times.
I also know that I couldn’t tell the difference when driving.
What if you are going from run-flats on a 17″ wheel to lower-profile non-run-flats on an 18″ wheel?
Yeah the above is only useful for factory wheels, if you’re going up in size then you’ll kinda have to play with it but definitely on a lower profile tire you’re going to want to up the pressure.
My ’13 Equinox and wife’s ’14 Equinox both state 35 Psi even though hers
is a FlexFuel and mine is not. We seem to get good comfort and low wear at that pressure. I got pairs of tires a couple of years apart a few years ago; hers are still good in tread depth and integrity, as are mine. I’ve put about 30k miles on mine since purchase in late-2016, hers has more, but they’re both sitting on good rubber. TPMS keeps us on top of the situation, and we maintain accordingly. Great to have on-vehicle monitoring as opposed to jumping out with a gauge all the time. I just roll up to my local Discount Tire, set the pressure, push Start, and inflate. Pump and vehicle confirms it. Easy-peasy.
I think that if Dr. Phill were supervising tire inflation, the good doctor would be haranguing me, telling me that I don’t check often enough, my dog doesn’t hunt, my inflation game is weak and that I should man up and air up, all in front of a studio audience.
Locations of such information may vary on older cars. On my 1969 VW bus and 1983 Mercedes 300TD it’s located on the inside of the gas filler flap/lid and on my late and lamented 1985 VW Jetta it was located on the rear passenger doorjamb. And I’ve seen the information on the front passenger side doorjamb (on some older Japanese cars.)
My 2014 pathfinder has a tpms system that the car honks when you get to the correct pressure. I forget how you activate it though…
I have to see if my 2024 EV6 has this too.
Nice trick!
Look, all I know is, the most important thing is that the fronts need to be 10 lower than the rear
The doorjam sticker in my S5 (265-30R20) says 45 psi front and rear. The dealer suggests 39 front 33 rear and it’s infinitely better that way.
My S5 and Q7 both list the “fully laden” pressures on the door jamb but don’t list any of the other possible configurations in the manual. After the umpteenth time of pulling up the manual PDF on my phone, I used a sharpie to write in the “normal” pressures on the door jamb stickers.
Reminder that if you have moved from a P metric rated tire to an LT, that your tire pressures will go UP with your new LT rated tires.
Calculate here
https://tiresize.com/pressure-calculator/
Mine went from 32 (door jamb) to 38 psi. LT rated tires need more air for a given load, so the pressure goes up.
If you have an SUV or truck and you’ve upsized your tire to 33 or larger, chances are you are on an LT. Most stock heavier trucks are already on LT
That’s a nice calculator. It not only applies to LT tires but any time you use a tire that differs in size, or load rating from that on the placard.
I was just going to comment on this. After having my truck serviced recently, I noticed that there was a lot more tire roar. I assumed it was just the result of the tires (BFG TA/KO2 LT) wearing, but then noticed that the tires had been aired down to 36 PSI at the shop. I do a lot of towing, and had been running them at 51 PSI cold (max load for these tires is at 65 PSI).
I had a 2015 Nissan Murano with a unique feature. When airing up a tire the horn would beep when it hit the correct pressure. I jumped out of my skin every flipping time.
Ha I just posted my 2014 pathfinder sl does that.. i didn’t read the comments before posting
I already have too much pressure in my life.
Right?
-HVAC Lyfe, yo!
😉
What’s everyone’s prescribed pressure? My Fiesta ST calls for 39psi on the front and the ride is a bit…firm.
My Civic Si wants 33 psi front, 32 rear. Just filled it today (again) since the light was on (again).
My 04 Highlander says 33 psi front and rear for stock 17″ tires. I put 35 psi in and they still feel soft and squishy to me.
60 front/80 rear
strap in: it’s gonna be a bumpy ride…
30PSI for my Lucerne, 36PSI for the family Grand Caravan, 35PSI for dad’s RCSB Silverado, and 32PSI for our spare Journey.
chalk
I agree, chalk is the answer for those of us who have significantly upsized tires for off roading. I run 285/70-17 and the door jamb shows 37 psi. On my 2 door wrangler, 28-30 is my street pressure. Immensely more pleasant on the tarmac. YMMV. As the article says, weight matters.
Chalk?
I run non-oem sizes on my Porsche 944 Turbo and had to use the chalk method to find the right pressures on both street and track.
Basically, run a chalk line or three across the treads and a little up the side walls. You’re looking for the pressure where you’re just wearing the chalk off the shoulder treads. Too much pressure, and you’ll have chalk left on those shoulder treads because you’re not ‘squishing’ the tire enough when cornering. Too little and you’re probably leaving chalk in the middle somewhere. It’s a good way to get in the ballpark.
I’ve never seen it remaining in the center. You know you have too little pressure when it wears off the side walls because the tire is flexing too much under cornering. You want to obtain a clean tread from shoulder to shoulder but leave it intact in the side walls.