Tire PSI - use tire or door rating?

[finneylp]

I had to repair a flat last week, and the tech that helped me out said I should run my tires at 36-38 PSI cold vs 32 PSI. I have 11k miles on the car, and he showed me how the outside is wearing faster than the center, due to under-inflation.

My EX-T door jam says 32 PSI all the way around. The tires are rated to 44 max.

Does anyone know how Honda comes up with their PSI? Any recommendations for preferred PSI? I do mostly solo highway driving.

This has always confused me, anyone have some good, fact based info about using the car vs tire recommendations?

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[somarilnos]

I had to repair a flat last week, and the tech that helped me out said I should run my tires at 36-38 PSI cold vs 32 PSI. I have 11k miles on the car, and he showed me how the outside is wearing faster than the center, due to under-inflation.

My EX-T door jam says 32 PSI all the way around. The tires are rated to 44 max.

Does anyone know how Honda comes up with their PSI? Any recommendations for preferred PSI? I do mostly solo highway driving.

This has always confused me, anyone have some good, fact based info about using the car vs tire recommendations?

There is no 'tire recommendations'. They have a max cold inflation pressure that you should not exceed, but it has no recommended figure.

Beyond that, what you go with is largely a matter of personal preference. A higher amount of pressure than recommended will give you better fuel economy, and will provide a buffer where if you gradually lose a little bit of tire pressure, you're still at or above recommendations. This comes at a cost of handling, past a certain point. Make sure you get a feel for how the car behaves when cornering at different levels of pressure.

You should absolutely not try going under the manufacturer's recommendations. Below that point, not only will the car not handle well, but it will wear in a bad way, and it will cost you fuel economy.

I've been personally going well over the recommendations at 42 psi cold. That's a safe figure, it corners well enough for my needs, and gets me much better mileage.

 

[inv4zn]

Are both outsides wearing faster than the centre? If so then it is underinflated. If it's just the outermost side of the tire, then you have an alignment problem.

I've experimented with tire pressures before, but I found that the decrease in handling/stopping is not worth the few extra MPGs you squeeze out.

So I just follow manufacturer specs -- make sure it's 32 PSI when cold (ie after the car has sat overnight)

 

[mechatune]

I'm with your tech at 36-38psi cold. I'm not brave enough to go 40psi+ lol

 

[TenGen]

After your vehicle has sit for 3 hours your tires should be cool to the surrounding temperature. At this point make adjustment to what the door claims. You can add 1 more psi if you like because typically you can lose half a psi when removing the nozzle. Do not put the max psi rating on the tires. That rating is there for a reason and not for what your thinking. Go off what Honda has claimed is the correct psi. This will be the correct amount of pressure to hold the proper shape of the tire for the load and weight of the vehicle under regular driving conditions. If you feel its not accurate then monitor the tread wear on your tires, it will tell you if your running too much too less or just enough. Accelerated wear on the center of the contact patch is overinflation, drop some air pressure. Accelerated wear on BOTH edges of the contact patch can be caused by under inflation. Alignment is a different story.


TLDR put it to the damn pressure honda calls for and be done with it.

 

[tacthecat]

I had to repair a flat last week, and the tech that helped me out said I should run my tires at 36-38 PSI cold vs 32 PSI. I have 11k miles on the car, and he showed me how the outside is wearing faster than the center, due to under-inflation.

My EX-T door jam says 32 PSI all the way around. The tires are rated to 44 max.

Does anyone know how Honda comes up with their PSI? Any recommendations for preferred PSI? I do mostly solo highway driving.

This has always confused me, anyone have some good, fact based info about using the car vs tire recommendations?

Recommended pressure is for normal use of your vehicle with size tire provided. It'll give best compromise of handling, safety, wear, and mileage for both tire and mpg.
1) As said elsewhere, make sure both front or rear tires are wearing the same and on both the inside and outside of each tire. If not you probably have an alignment problem, front or rear.
2) Also, be sure your gauge is reading accurately - it's not uncommon for them to be off 2 - 3 psi or, on occasion, more. It's best to have and use your own gauge. And be sure tires are "cold" - not driven.

 

[dick w]

The number on the sidewall is a number for safety--that pressure which the tire is designed to withstand and stay on the rim in one piece. It does not take into account anything about the car it's on, its load, or operating conditions.

Honda's recommended pressure is a compromise number they come up with based, somehow, on what they think is a nominal vehicle payload weight and typical driving use, and aims for the "best" tire contact patch for ride comfort, handling, and safety. If you weight 110 lbs, and always drive in cold conditions at low speed with no passengers or cargo, it may be too high. If you run at high speeds in hot conditions with max payload, it may be too low. In any case, it's a more suitable, and safer, answer than the tire sidewall safety pressure.

 

[kirkhilles]

I don't understand. Certainly you should never fill a tire anywhere close to its max limit cold as that'd mean that you'd be way over it while hot... and it's a MAX limit, not a "use this PSI" number. I always use the value provided by the manufacturer. I'd find it hard to believe that this is anything other than pretty-darn-close-to-ideal based on the specs of the car presuming you drive under "average" circumstances.

If you want to hypermill or doing significant suspension adjustments to the vehicle or have some other unusual circumstance or go with tires other than your average-passenger-tire (like racing tires or whatever) or different wheels, I'd understand. Otherwise, if you're sticking with stock, then I wouldn't recommend trusting some tire guy versus what Honda has calculated to use.

 

[TyBu]

Yeah. These tires also lose air faster when you inflate them past 32. I know that because the dealer gave them to me at 40 and after just a few days the TPMS went off on me.

Also, filling station air pumps are a giant pain in the ass and it's very difficult to hit the pressure you are aiming for.

Just get a decent bike pump and use that. Waaay easier unless you're starting with a flat tire.
https://www.rei.com/product/657109/...cse_PLA_GOOG&gclid=CMKo5e6Q7M0CFQdqfgod7agAww

edit: (the service department was pissed about the car being delivered to me at 40 PSI, btw. Said there was no reason for it.)

 

[somarilnos]

Yeah. These tires also lose air faster when you inflate them past 32. I know that because the dealer gave them to me at 40 and after just a few days the TPMS went off on me.

Also, filling station air pumps are a giant pain in the ass and it's very difficult to hit the pressure you are aiming for.

Just get a decent bike pump and use that. Waaay easier unless you're starting with a flat tire.
https://www.rei.com/product/657109/...cse_PLA_GOOG&gclid=CMKo5e6Q7M0CFQdqfgod7agAww

edit: (the service department was pissed about the car being delivered to me at 40 PSI, btw. Said there was no reason for it.)

That could have been a matter of them filling to 40 when the tires were warm (i.e. losing air quickly because of the temperature change), or the TPMS triggered on account of not being calibrated properly for the higher pressure. If there are no leaks, at 40 PSI, you shouldn't see this triggering in a few days if it's calibrated properly. I've been keeping mine steady at about 42, and it's holding for weeks at a time without noticeable changes.

 

[TyBu]

That could have been a matter of them filling to 40 when the tires were warm (i.e. losing air quickly because of the temperature change), or the TPMS triggered on account of not being calibrated properly for the higher pressure. If there are no leaks, at 40 PSI, you shouldn't see this triggering in a few days if it's calibrated properly. I've been keeping mine steady at about 42, and it's holding for weeks at a time without noticeable changes.

They actually ended up replacing one of the tires, too, and I suspect the other 3 tires losing pressure may have had more to do with inaccurate gas station gauges than the tires actually losing pressure. So you're probably right.

In any event, 32 seems just fine to me, and was definitely what the service department recommended. Not that I'm claiming they're the ultimate experts

 

[dick w]

Not that I'm claiming they're the ultimate experts

The closest thing we have to ultimate experts is the people who designed and installed the door jamb label.

 

[Farcry1010]

There is no 'tire recommendations'. They have a max cold inflation pressure that you should not exceed, but it has no recommended figure.

Beyond that, what you go with is largely a matter of personal preference. A higher amount of pressure than recommended will give you better fuel economy, and will provide a buffer where if you gradually lose a little bit of tire pressure, you're still at or above recommendations. This comes at a cost of handling, past a certain point. Make sure you get a feel for how the car behaves when cornering at different levels of pressure.

You should absolutely not try going under the manufacturer's recommendations. Below that point, not only will the car not handle well, but it will wear in a bad way, and it will cost you fuel economy.

I've been personally going well over the recommendations at 42 psi cold. That's a safe figure, it corners well enough for my needs, and gets me much better mileage.

Always go by 'the door' sticker. Not the tire. This same exact tire is mounted on different vehicles of different weights. A heavier car will tend to 'roll' the tire on the rim 'sidewall roll' in a corner so usually a heavier car will have a higher psi on the door sticker that has the same exact tire which will increase sidewall roll resistance.
I have no idea who posted 'that loads do not matter'. That's why when you have a full car of 5 passengers and a full trunk of cargo they tell you to increase PSI up by 4 lbs. if not more this is usually on the door sticker. On my Audi all tires 36 PSI then on the door sticker with a full load of passengers and cargo that you should inflate to 42 PSI. So I would always use the door sticker! And stick close to it. If you go to 36 psi you will lose traction and grip but get really good mpg! Lol. And also wearing out middle of tire. So no don't do this. This car already gets great MPG.

 

[Farcry1010]

NEVER use the inflation info on the tire...That tire could be used on many different kinds of cars. Always use what the label in the door jam says. The door jam suggests the EXACT tire pressure for that EXACT car....(providing you're using tires which are recommended for that car).

Yes. Exactly!!! I can't believe some people at putting in over 40PSI in there Civics. Lol.

 

[tacthecat]

that tech should be fired. He doesn't know WHAT he's talking about! Not (only) will you get a rough ride over inflating, but the tire will wear unevenly, heat up faster, provide less traction surface to the road, but could also cause hydroplaning on wet/snowy surfaces. ALWAYS use the recommended tire psi as per door sticker. That is the one HONDA recommends for that exact vehicle.

Delete the "heat up faster" statement and I'll give you a LIKE!

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