Possible Tire Pressure Mistake?

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ElectriCute

Well-known member
Joined
Oct 29, 2021
Messages
72
New 2022 Leaf SV

I just read in a post in "Tips and Tricks," to keep the tires inflated at 40 at 42psi, even though the door sticker states 36psi front and rear. While driving on the highway, the car does not keep a straight line. There's slight drift from side to side. Never experienced this on other owned cars. Not terrible, but annoying. Late yesterday afternoon, in hopes of correcting this, I deflated the tires to 35psi, thinking that a harder tire might be at fault. I haven't tried it out as yet, perhaps today. First of all, any thoughts as to why I notice a slight drifting? And should I, as that post recommended, keep the tires at 40 to 42psi?

Thank you.
 
I have always kept the tires at 40-42 PSI for efficiency and improved longevity, and have never noticed any wander. Seems counter-intuitive that HARDER tires would wander more..... I will bet that you don't notice any diff at the lower pressures.
 
Tire pressure needs to be set ideally in proportion to the load. That is, either too high or too low can cause wander and uneven tire wear.

Too low and the sidewalls will soften; too high and the tread will “dome”. Either can cause handling issues. Manufacturers publish load charts that specify the ideal pressure for a given load per tire for a given size of that tire.

There is a range of useful pressures for any given situation though. Devils in the details. Setting too low also risks tire failure due to overheating.

The stock Michelin’s aren’t rated high enough to be driven at a pressure that would cause doming on our cars. I think most of us set them in the low 40’s cold with good results. Do not exceed the maximum cold inflation pressure as that also risks tire failure for obvious reasons.
 
The only situation I can think of in which you'd want the pressure lower than 40psi is if the tires are only rated for 40psi or less. Tires like that are rare these days. You likely have an alignment issue or a damaged tire. 36psi is more likely to cause problems than 40. Did you try another pressure gauge?
 
frontrangeleaf said:
Tire pressure needs to be set ideally in proportion to the load. That is, either too high or too low can cause wander and uneven tire wear.

Too low and the sidewalls will soften; too high and the tread will “dome”. Either can cause handling issues. Manufacturers publish load charts that specify the ideal pressure for a given load per tire for a given size of that tire.

There is a range of useful pressures for any given situation though. Devils in the details. Setting too low also risks tire failure due to overheating.

The stock Michelin’s aren’t rated high enough to be driven at a pressure that would cause doming on our cars. I think most of us set them in the low 40’s cold with good results. Do not exceed the maximum cold inflation pressure as that also risks tire failure for obvious reasons.

Strange as it might sound, I took it for a ride on the highway. Same route I took where I noticed the slight drifting. Tire pressure set at 26psi as shown on the manufacturers sticker, the car behaved properly. Drove nicely with no drifting. Perhaps due to different tires being used on new models.
 
I'm hoping that you meant 36psi, not 26. Setting the tires to 36 isn't likely to cause any problems. The issues are that the range will be less, under some conditions the handling will be more 'sloppy' and, most important, there is little margin for letting the pressure drop more over time. Once it falls below 32psi, then increased wear and poor emergency handling will result.
 
LeftieBiker said:
I'm hoping that you meant 36psi, not 26. Setting the tires to 36 isn't likely to cause any problems. The issues are that the range will be less, under some conditions the handling will be more 'sloppy' and, most important, there is little margin for letting the pressure drop more over time. Once it falls below 32psi, then increased wear and poor emergency handling will result.

Yes, I did mean 36psi. Sorry, typo error. I agree that if the pressure falls low, it will have a negative affect on handling and increase wear. I'm a stickler for periodically checking tire pressure. For now, I found that it holds the road better. No drift.
 
If you want a good compromise, I often ran 38psi on my Gen II Leaf, until I decided that I'd rather not have to add air that often. Now I set it to 40-42, but only once every few months. I also look at the tire pressure display on the dash regularly.
 
I, too, have noted drifting at highway speeds (60+ mph) when the tires are over-inflated. My car seemed very "nervous" on the initial ride home and subsequent highway trips. When I eventually checked tire pressure, I saw the dealer had them inflated to 46psi!!! I dropped them to 40 and noticed smoother ride quality and less highway drift. Now I inflate them to 38 and wait until they drop to 35 before adding air.

The steering in these cars seems overly boosted with virtually no useful feedback. Is it drive by wire? Maybe the narrower tires on my S model exaggerate this? My test drives were mostly <50 mph but all the models seemed ridiculously easy to turn the steering wheel. Makes for easy parking lot maneuvers but bad highway manners.

I can understand wanting to avoid under inflation. But the push for severe over inflation (44psi) seems ill advised. Yes, you'll get better range in a back-to-back test compared to 36psi. But eventually you will wear down the center tread until you have a flat contact patch again. So the range benefit will be reduced and the safe tire tread lifespan will be reduced since you've accelerated the wear of the center tread. Plus, as noted, the slight increase in range (while it lasts) is accompanied with a reduction in highway safety due to drifting. That's not a compromise I'm willing to make. With the 62kWh battery I don't have to play games to push for max range.

Do you believe the engineers and marketing folks at Nissan threw away "free range" by specifying the tire inflation too low? These are the same folks that removed the Mountain Mode feature (charge termination at 80% SOC) just because the EPA factored it into their range rating for the early Leaves. Nissan is perfectly willing to compromise the car for a bit of range. So there's got to be powerful reasons they're sticking to 36psi. This is no different for any car, EV or ICE. You can cheat the tire inflation upwards for better mileage, but there are drawbacks.
 
I can understand wanting to avoid under inflation. But the push for severe over inflation (44psi) seems ill advised. Yes, you'll get better range in a back-to-back test compared to 36psi. But eventually you will wear down the center tread until you have a flat contact patch again. So the range benefit will be reduced and the safe tire tread lifespan will be reduced since you've accelerated the wear of the center tread. Plus, as noted, the slight increase in range (while it lasts) is accompanied with a reduction in highway safety due to drifting. That's not a compromise I'm willing to make. With the 62kWh battery I don't have to play games to push for max range.


It is common for auto manufacturers to have too-low recommended tire pressures, because they provide a nice, compliant ride - at least at low speeds. Toyota/Chevy had 32psi stamped on the Corolla clone that my ex-GF drove until a few years ago. She INSISTED on staying with that limit, and as a result, whenever I checked her tires the pressure was in the mid twenties - or lower. Needless to say, she burned through tires. She still does. Now, that being said, I agree that over-inflating tires - that is, exceeding the maximum pressure stamped on the tire - is a bad idea. Please note that I don't recommend that. What I usually suggest is that people run them at 10% below the maximum stamped on the sidewall. If my Tips & Tricks guide doesn't say that, I'll change it. It should be noted, though, that people here who run at or near the maximum pressure have reported DECREASED wear on the tires. Why? The Leaf is a heavy little car, and 40psi does a better job of matching the load on the tires than does 36psi. It's also MUCH better than the 30-33psi that is likely to be common when the tires are inflated to 36psi at typical intervals.
 
So let's compare Leaf against a lighter ICE car. How about the Altima?

Wikipedia says the Leaf weighs 3480 - 3620 pounds, and Altima weighs 3160 - 3470. On average, Leaf is heavier by 7%. The Altima rides on 215/60/16 or 215/55/17 tires if you skip the crazy performance tires. So slightly bigger than the Leaf tires (205/55/16 or 215/50/17). I don't know the math (how much volume is lost between the exterior tire dimensions and the interior air space?) but the Altima is riding on slightly more air volume. Nissan recommends 32 - 33 psi for the Altima, and 36 psi for Leaf. So about 11% more pressure in the Leaf tires. That extra pressure counters the extra weight and perhaps some of the lesser air volume.

So maybe Leaf is just a bit under specified compared to the Altima. And Altima may not be the perfect reference. But I don't think Nissan is wrong by 22% (44 psi vs 36 psi). 36 to 38 psi feels right to me and certainly not mushy. 44 psi feels drifty and bouncy in ways that compromise my safety. I'm sure there's differences for S vs. SV/SL models and for Plus vs. non-Plus models. But for my car, I've found my preferred range and it's not 40+.

When considering the differences in weight, I like to think about how differently the car drives if I'm alone vs taking the wife and teenagers. That's like +330 pounds of "cargo" and it doesn't seem to dramatically change my experience with comfort/drift/bounce/mush.
 
As has been discussed before here, the theory is that the lower PSI is to keep lawsuits away from Nissan as to keep the stopping distance good during emergencies at high speed. While on a hot day, the tires will naturally inflate from 36 PSI to 40 PSI while driving and everything feels fine. That's why we recommend starting at that 40 PSI because it gets you to the zone quicker instead of the heat build up and energy loss to reach it first. On mild and colder days though, the pressure will remain lower, so the ride is softer but so is the steering and acceleration.
Another issue is, Nissan can't test every tire in existence, so again, they use 36 PSI as a safety zone because people getting less mileage and poor acceleration is not going to generate lawsuits. Every tire manufacture has some specs to follow, but all perform differently in the field when tested. Some do better at lower PSI than others at a higher PSI. It's easier to start at 36 PSI, get a feel for how the vehicle performs, then slowly inflate a few PSI until you reach a point where you do not like the performance. For me, My Leaf+ weights a lot more than my Wife's Leaf so I run higher PSI than her. She wants a soft ride, but her tires max at 51 PSI, so I run 42 PSI in them, she seems to like that. My tires max at 44 PSI and I run them at 44 PSI to get the same ride comfort as her. The weather is colder now, so all of our tires have already dropped 1 to 2 PSI during the day anyway, so unless they lose more air, I won't touch them again until they get under 40 PSI or we really know a big range drop from the decreased air pressure.
Different strokes for difference folks, as long as you stay above the minimum 36 PSI and below the tire cold pressure max, you'll find the sweet spot that you want for range, comfort and performance in the long run. :D

ElectriCute said:
New 2022 Leaf SV

I just read in a post in "Tips and Tricks," to keep the tires inflated at 40 at 42psi, even though the door sticker states 36psi front and rear. While driving on the highway, the car does not keep a straight line. There's slight drift from side to side. Never experienced this on other owned cars. Not terrible, but annoying. Late yesterday afternoon, in hopes of correcting this, I deflated the tires to 35psi, thinking that a harder tire might be at fault. I haven't tried it out as yet, perhaps today. First of all, any thoughts as to why I notice a slight drifting? And should I, as that post recommended, keep the tires at 40 to 42psi?

Thank you.
 
Snargleblarg said:
Do you believe the engineers and marketing folks at Nissan threw away "free range" by specifying the tire inflation too low? These are the same folks that removed the Mountain Mode feature (charge termination at 80% SOC) just because the EPA factored it into their range rating for the early Leaves. Nissan is perfectly willing to compromise the car for a bit of range. So there's got to be powerful reasons they're sticking to 36psi. This is no different for any car, EV or ICE. You can cheat the tire inflation upwards for better mileage, but there are drawbacks.

I believe the lawyers came in on that one, sure Nissan wants more range, but not if it will be bankrupt from lawsuits. USA is a sue-happy country unfortunately. :(
 
So maybe Leaf is just a bit under specified compared to the Altima. And Altima may not be the perfect reference. But I don't think Nissan is wrong by 22% (44 psi vs 36 psi). 36 to 38 psi feels right to me and certainly not mushy. 44 psi feels drifty and bouncy in ways that compromise my safety. I'm sure there's differences for S vs. SV/SL models and for Plus vs. non-Plus models. But for my car, I've found my preferred range and it's not 40+.

Once again, I don't recommend 44psi - I suggest 40-42, or 10% below the max posted on the tire. If you want to rebut solid anecdotal evidence with evidence based on math, go ahead. As was just written, different strokes for different folks. 38psi is a good setting, and I've used it myself. 36psi is ok if checked regularly, but it doesn't solve any problems and with the Leaf it can actually mean more tire wear rather than less. I still think that electricute has either a misaligned front end or a marginal tire that is causing her issue.

Knightmb slipped in ahead of me. I'm not sure that it's legal CYA. I and others believe that it's an issue of people liking a soft ride. I'm not certain of that, though, and CYA would be my second guess.
 
LeftieBiker said:
So maybe Leaf is just a bit under specified compared to the Altima. And Altima may not be the perfect reference. But I don't think Nissan is wrong by 22% (44 psi vs 36 psi). 36 to 38 psi feels right to me and certainly not mushy. 44 psi feels drifty and bouncy in ways that compromise my safety. I'm sure there's differences for S vs. SV/SL models and for Plus vs. non-Plus models. But for my car, I've found my preferred range and it's not 40+.

I still think that electricute has either a misaligned front end or a marginal tire that is causing her issue.

I sure hope not. But it's worth checking out. Although, it rides rather well on city streets, and also on the highway now after lowering the pressure. The dealer pressurized the tires with a percentage of nitrous oxide. They say it helps to maintain tire pressure over time. Free
refills and free charging if I drop by. That's nice of them, but I don't think I'll bother. I don't feel like sitting around the dealership for a half hour or so and drink their coffee while they charge my battery, when I can sit in the comfort of my own home, charge the battery and drink my own, much better, coffee. 😊

Oh, by the way, I'm a him. ElectriCute is what my wife calls the car. 😂😂
 
LeftieBiker said:
If you want to rebut solid anecdotal evidence with evidence based on math, go ahead.

No, I think the math exercise I attempted does support that the Leaf pressures would need to be somewhat higher than 36 to account for the smaller air volume compared to Altima. Its my actual drive experience I'm reacting to. And I suggest the same to the OP. If 40+ feels wrong to you and is not recommended by Nissan then don't go 40+.

I can't imagine the Nissan dealership is going to be much help to the OP If he shares his full experience -that the problem exists at 42 psi but goes away at 36 psi - they will set the inflation to 36 and send him on his way. If he doesn't share that info, maybe they will rebalance the wheels and I would be interested to hear if that helps. Perhaps we both have a wheel that's slightly unbalanced. Not sure what I would do even if I suspected that was the case. I wouldn't pay for rebalancing when they work fine at 38 psi. Maybe I'd bother to try experimenting with inflation again when I move to a 2nd set of tires? Alignment might be off I guess. But that doesn't explain why my car is easily disturbed by the airflow from a passing SUV if my tires are at 44 psi.
 
Regarding the original question about wandering on the highway, I have a couple thoughts that may or may not relate to tire pressure.

We bought a 2014 Leaf SV about two months ago for my wife to use for her relatively short commute. I quickly noticed that the steering had little feedback, which sometimes leads to a bit of back-and-forth in the steering wheel that can make the car wander around in the lane a bit. This is especially noticeable when my wife is driving, as she is "twitchy" with the steering wheel. She doesn't notice it at all, but it almost makes me feel seasick. Note that I run the Leaf tires at 40-42 psi for the reasons already discussed in this thread. I don't have the same feeling (as driver or passenger) in our Honda Fit which has heavier steering. For comparison, I run the Fit tires at 34-40 psi depending on whether we're driving locally on our super poor MA roads or going on a longer trip.

Anyway, how does tire pressure relate to the Leaf's handling? Is it possible that when you run your tires in the mid-30s the flexing of the sidewalls along with the softish suspension can absorb a bit of the small-scale twitchiness in the steering system, whereas as you crest 40 psi and the sidewalls get stiffer any back-and-forth movement you're imparting to the steering wheel because of the lack of feedback is more directly translated into back-and-forth wandering in the lane? Just a thought. I will lower the Leaf psi on a short trip with my wife driving to see if some of the wandering feeling goes away.

I grew up driving old 1970s farm trucks where you could move the steering wheel several inches to the right or left without doing anything to the front wheels. Not a problem at crawl speed when picking up hay bales, but a handful when driving a full load down the highway. At least the Leaf isn't like that.
 
Tire pressure on an EV is obviously debatable. One of the common Leaf tire sizes was on my Honda Civic at the same pressures and 1000 lbs lighter vehicle. Through 2 different Leafs, I’ve found 40-42 cold inflation seems to work best, at least for the cratered roads and temperature fluctuations of my own situation. A heavier 62 KWh model likely would need slightly more to compensate for the additional 350 lbs. I took it one step further by resetting the TPMS alert threshold to 36 using leafspy. That seems to compensate for the addition weight of an EV.
 
Maybe we could all agree that tire pressure is a matter of personal taste. I think it's obvious that there is a max and min limit for safety but within those limits we can all decide how much comfort we want to trade for efficiency and how we like the car to handle. Of course, I'd guess the vast majority of drivers have no clue what tire pressure they run at and what the trade-offs are but for those who know and care, there can certainly be differences of opinion on what is best for each driver.
 
goldbrick said:
Maybe we could all agree that tire pressure is a matter of personal taste. I think it's obvious that there is a max and min limit for safety but within those limits we can all decide how much comfort we want to trade for efficiency and how we like the car to handle. Of course, I'd guess the vast majority of drivers have no clue what tire pressure they run at and what the trade-offs are but for those who know and care, there can certainly be differences of opinion on what is best for each driver.

Totally agree. For me, making an adjustment of lowering the pressure to what Nissan suggested, made for a better ride at highway speeds.
 
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