Tire Pressure....

maple14maple14 Member Posts: 7
edited February 2016 in Toyota
When I test drove my 2014 Corolla. It drove like the tires were low. So, after buying it. I looked at the tires. They said 51psi max. These are Toyo tires. 201/55 R16. So I inflated them to 47 front, 44 rear.
Looking in the owners manual. It says 32 all around.
Now did they change tires? Miss print?
From the owners manual. I probably should change them to the same pressure all around. I can say from experience. They should be close to 51. It drives much better. I probably get much better mileage also. I haven't had it long enough to even verify that. Only the dash computer which is telling me excellent...probably 36 half hwy/city.

Comments

  • maple14maple14 Member Posts: 7
    That should have said: 205/55 R16
  • steverstever Guest Posts: 52,457
    The general recommendation for the optimum balance between safety, comfort and mpg is to use the psi indicated (usually) on the tire placard on the driver's side door jamb. It''ll probably be the same as what's in the manual.

    Overinflating tires will make the centers wear out faster.
  • maple14maple14 Member Posts: 7
    Am I to assume that you are advising me to begin ignoring the tire itself? After 40 years of different tire max psi's and inflating them successfully?

    Underinflated tires are unsafe handling, ruin gas mileage, and wear on the outside edges.
  • steverstever Guest Posts: 52,457
    "A tire's maximum inflation pressure is the highest "cold" inflation pressure that the tire is designed to contain. However the tire's maximum inflation pressure should only be used when called for on the vehicle's tire placard or in the vehicle's owners manual.

    [W]hen checking and adjusting tire inflation pressures, the "right" inflation pressures are those provided by the vehicle manufacturer, not the "maximum" inflation pressure branded on the tire's sidewall."

    More at TireRack, where I got those quotes.
  • maple14maple14 Member Posts: 7
    What Tire Rack is talking about, commonly is on the rear tires of pickup trucks. When a pickup truck is empty. The rear tires are greatly deflated from max psi. Then when a person loads a pickup truck bed. The tires badly need to be inflated. Often times to max psi. Yes, the vehicle placard says this.
    I had a toyota truck that had 32psi max tires stock. I put 40 psi max tires on it. Now do you think I blindly followed the exact pressures that toyota dictated on the placard? No... But I did follow the ranges on the placard, taken as a percentage, and applied to the tire itself. This is called; Comprehension. Or... Common Horse Sense.
    All of this does apply to how the vehicle drives, wear on the tires, and all. Try inflating the rear tires on a pickup truck to max with no weight in the bed? You will have difficulty stopping. Wear your brakes badly. It will handle badly. Always throwing the weight of the truck too far forward. You will have difficulty with traction on the rear wheels.
    The bottom line is to Comprehend. Pay attention to how the tires are wearing. How the vehicle drives. Using actual Comprehension...I see nothing in Tire Racks article that backs you up. ????

    I have also had front wheel drive cars that stated on the placard to inflate the front tires a little more than the rear. I followed that and it worked good. This car is different. All tires are to be the same.

    I have not inflated these tires to max psi. cold.

    Another common example of tire pressure and Comprehension. If one drives in the desert in the middle of summer. One must deflate the tires in the morning, before driving, when they are cool. The increase in temperature during the day, inflates them too badly. If you doubt me. Call up the tire and auto shops in Baker Calif. Or any other desert place. They make a ton of money off people blowing their tires because they did not do this. Obviously...my tires on my car...if inflated cold to 32psi... I will have no problem driving in the desert in the middle of summer.

    My original question. For many years, Toyota, as well as every other manufacturer used 32psi max tires. They dictated 32psi max on the placard and owners manual. I am wondering if there was simply a mistake on the owners manual? I was looking for more intelligent than to take facts and attempt to apply them to rationalize that tires designed for max 51psi should be run at 32psi. That's 63% of max cold tire pressure.
    Other indicators...
    The tires had lost air. Between 30 and 25. Shows the beads not set well in the wheels.
    Wear on the outside edges of the tires.
    These are besides what I mentioned in the OP.

    The only time I have seen people run tires like this. They wanted an extremely soft ride. They also tore up their tires prematurely, and paid for it.
  • steverstever Guest Posts: 52,457
    edited February 2016
    I think you're wrong. But what do I know - I've only been driving for 50 years. ;)

    Have this picture in my head of you bouncing down the road.

    Here's a thread you may enjoy skimming over in Tires, Tires, Tires.

    From that link - "cold inflation specs aren't arbitrary numbers, there is a lot of experience and engineering going into the calculations that are used to arrive at the specification". Oh and the poster is a retired tire engineer.
  • texasestexases Member Posts: 9,532
    The owner's manual and the sticker on the car are the recommended pressures to use, the number on the tire is the max cold pressure. So you are over inflating your tires, according to the manufacturer. I use the sticker number plus a couple of psi.
  • carboy21carboy21 Member Posts: 760
    32 psi is normal recommended but I usually do it to 35 psi. I like the low rolling resistance.
  • maple14maple14 Member Posts: 7
    Thank you carboy21.... I'm wondering how your tires are wearing? I take it; ok? Everything else matches up? Same make of tire?

    Mine is driving better with all four the same pressure. See how they run at 42. Measured with a different gauge that isn't near it's max.

    I'm disappointed in most of the replies here. I was hoping for some intelligent replies. I'm getting excuses for conflict. Not constructive discussion.
  • thecardoc3thecardoc3 Member Posts: 5,426
    Take a closer look at the information on the side of your tire. While it says what the maximum pressure can be, it also states the maximum weight that the tire should be supporting. Standard load tires can be inflated to 41psi , but actually reach their maximum load at 35psi. Extra load capacity tires reach their maximum load capacity at the maximum inflation spec printed in the side of the tire. So the first question is does your Corolla have standard load tires, or extra load tires?

    A Corolla curb weight is under 3000lbs. Standard load P205 55R16's (at 35psi) can typically about carry 1300 lbs. Multiply that by 4 and you are going to be somewhere in the 5200 lbs. range. That means that the tires are technically over inflated if they are being used on a Corolla at that pressure. So its no surprise that the specification on the door is only 32psi.

    What muddies the waters here is that the tires can perform reasonably well even when they aren't inflated correctly under normal use. There is a mathematical curve that could be plotted for each tire that will show where its peak performance is at when given a typical load and pressure as well as just how far one can vary from that ideal pressure specification before performance or tire life begins to noticeably suffer. For whatever reason, you appear to have learned to like the feel of having your tires over inflated. Which reminds me of a long time customer, the first time I serviced his Porsche.

    His Porsche is his pride and joy and when he brought it for state inspection the first time he decided to wait for the car. I took it for the mandatory road test and couldn't stand the ride. It felt like it was riding on four basketballs, instead of tires. I pulled into the shop, and as I got out of the car I asked him how much air was in the tires. He gave me a puzzled look and I told him that they had to be over inflated. Checking, they were all in the low 50's. The spec was 30psi. After the inspection was completed, and the tires properly inflated we both went for a ride, with me driving. The difference in the car was noticeable before we got to the end of the block. It blew him away that all I needed to do was drive the car and I knew the tires were over inflated. With practice that is as easy to notice as a tire(s) that is underinflated.

    At your stated pressures above, the ride would be very harsh just like that Porsche, especially from the rear where there is less weight. The camber angles on your car are set to a negative specification to allow the tires to roll to vertical under side loading (turns). Excessive pressure will reduce the roll and that reduces the contact area reducing traction. For that reason alone you need to get the pressures down closer to the specification. The real fun from there is just what is "cold" and how much does that impact tire pressures? Lets just say that if you aren't using a gage certified to be within 1%, and an infrared thermometer to measure the temperature of each tire from which to compensate to "cold", you are PROBABLY NOT inflating your tires correctly.
  • texasestexases Member Posts: 9,532
    maple14 said:

    Thank you carboy21.... I'm wondering how your tires are wearing? I take it; ok? Everything else matches up? Same make of tire?

    Mine is driving better with all four the same pressure. See how they run at 42. Measured with a different gauge that isn't near it's max.

    I'm disappointed in most of the replies here. I was hoping for some intelligent replies. I'm getting excuses for conflict. Not constructive discussion.

    How is providing factual documented comments not "intelligent"? Insults not appreciated.
  • thecardoc3thecardoc3 Member Posts: 5,426
    texases said:


    How is providing factual documented comments not "intelligent"? Insults not appreciated.

    Just take it like a tech/shop has to. A tire shop near me had a fellow with a Cadillac that wanted his tires set to 36psi, but that put the TPMS light on. Everybody that tried to help would have taken being told they weren't intelligent as a compliment compared to how that gentleman ????? acted.

  • texasestexases Member Posts: 9,532
    You have my sympathy, @thecardoc3 - I guess 'intelligent' comments are ones that agree with the OP...
  • thecardoc3thecardoc3 Member Posts: 5,426
    texases said:

    You have my sympathy, @thecardoc3 - I guess 'intelligent' comments are ones that agree with the OP...

    Thanks. It's things like this that kind-of make all of the study and hard work that the job demands a questionable effort.

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