I do the good old chaulk line on my tires to determine the range of PSIs whenever I get new tires. If you are that sensitive that your car 'bounces over bumps' and your adjusting your PSI a few lbs fixes it, then you may have other suspension/alignment problems, unless it is a known issue with your car. Best of luck.
PSI, Up/Down???
- Thread starter CharBaby
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Originally Posted By: Char Baby
In other words, if my door jamb label says...F:30/R:30 but for ride comfort I like...F:32/R:29, is this OK?
Or, any combination of there or about!
Another example is, I have a vehicle that states on the door jamb label...F:32/R:32 but, I like, F:30/R:28...Is this OK as well?
In theory, you should NEVER use PSI lower than what the door jamb label specifies. If you go below, you are reducing the load carrying capacity, and increasing the chance of the tire overheating and blow out. Again, in theory. How likely is it to happen to you? I don't think anyone can accurately answer that.
In other words, if my door jamb label says...F:30/R:30 but for ride comfort I like...F:32/R:29, is this OK?
Or, any combination of there or about!
Another example is, I have a vehicle that states on the door jamb label...F:32/R:32 but, I like, F:30/R:28...Is this OK as well?
In theory, you should NEVER use PSI lower than what the door jamb label specifies. If you go below, you are reducing the load carrying capacity, and increasing the chance of the tire overheating and blow out. Again, in theory. How likely is it to happen to you? I don't think anyone can accurately answer that.
Originally Posted By: Quattro Pete
Originally Posted By: Char Baby
In other words, if my door jamb label says...F:30/R:30 but for ride comfort I like...F:32/R:29, is this OK?
Or, any combination of there or about!
Another example is, I have a vehicle that states on the door jamb label...F:32/R:32 but, I like, F:30/R:28...Is this OK as well?
In theory, you should NEVER use PSI lower than what the door jamb label specifies. If you go below, you are reducing the load carrying capacity, and increasing the chance of the tire overheating and blow out. Again, in theory. How likely is it to happen to you? I don't think anyone can accurately answer that.
Depends on the vehicle. Some have a lot more tire load capacity than others.
For example I will use my 2012 Escape. The stock tires have a 104 load rating. That equals a 1984 pound capacity at 35 psi. Stock psi is 32 which equals 1885 pound capacity. A reduction of 99 pounds per tire.
The Escape weighs just under 3400 pounds with a 60/40 weight distribution. Which equals 1360 pounds on the rear tires and 2040 on the front tires. So each rear tire is carrying 680 pounds and each front tire is carrying 1020 pounds. At the stock psi of 32 they are rated for 1885 pounds each. According to the tire load chart, if I lowered the psi to 26, the tires would still be rated to carry 1709 pounds each. Even if I dangerously overloaded my Escape it would be impossible to overload the tires at 26 psi or above.
http://toyotires.com/sites/default/files/page-files/LoadInflation_Table_P-LT_102913.pdf
So you can see the large safety margin that is built into the tire load capacity for this vehicle. Now most vehicles do not have this big of a margin. Our 4500 pound Sienna has tires that are only load rated 100. Much more important to maintain the psi on a vehicle like that.
Just wanted to show everyone that using the load charts you can make an informed decision on whether you want to lower the psi to improve a rough ride. To the general public yes I would say run the stock psi or above but for an educated group like all of us, you can make your own decisions.
Originally Posted By: Char Baby
In other words, if my door jamb label says...F:30/R:30 but for ride comfort I like...F:32/R:29, is this OK?
Or, any combination of there or about!
Another example is, I have a vehicle that states on the door jamb label...F:32/R:32 but, I like, F:30/R:28...Is this OK as well?
In theory, you should NEVER use PSI lower than what the door jamb label specifies. If you go below, you are reducing the load carrying capacity, and increasing the chance of the tire overheating and blow out. Again, in theory. How likely is it to happen to you? I don't think anyone can accurately answer that.
Depends on the vehicle. Some have a lot more tire load capacity than others.
For example I will use my 2012 Escape. The stock tires have a 104 load rating. That equals a 1984 pound capacity at 35 psi. Stock psi is 32 which equals 1885 pound capacity. A reduction of 99 pounds per tire.
The Escape weighs just under 3400 pounds with a 60/40 weight distribution. Which equals 1360 pounds on the rear tires and 2040 on the front tires. So each rear tire is carrying 680 pounds and each front tire is carrying 1020 pounds. At the stock psi of 32 they are rated for 1885 pounds each. According to the tire load chart, if I lowered the psi to 26, the tires would still be rated to carry 1709 pounds each. Even if I dangerously overloaded my Escape it would be impossible to overload the tires at 26 psi or above.
http://toyotires.com/sites/default/files/page-files/LoadInflation_Table_P-LT_102913.pdf
So you can see the large safety margin that is built into the tire load capacity for this vehicle. Now most vehicles do not have this big of a margin. Our 4500 pound Sienna has tires that are only load rated 100. Much more important to maintain the psi on a vehicle like that.
Just wanted to show everyone that using the load charts you can make an informed decision on whether you want to lower the psi to improve a rough ride. To the general public yes I would say run the stock psi or above but for an educated group like all of us, you can make your own decisions.
Originally Posted By: stranger706
[Depends on the vehicle. Some have a lot more tire load capacity than others.
For example I will use my 2012 Escape. The stock tires have a 104 load rating. That equals a 1984 pound capacity at 35 psi. Stock psi is 32 which equals 1885 pound capacity. A reduction of 99 pounds per tire.
The Escape weighs just under 3400 pounds with a 60/40 weight distribution. Which equals 1360 pounds on the rear tires and 2040 on the front tires. So each rear tire is carrying 680 pounds and each front tire is carrying 1020 pounds.
This may be true if the vehicle is sitting put. However, when in motion, load is not static. It constantly varies as you turn, brake, and accelerate, and so in certain cases it can be higher than what the above math would suggest.
[Depends on the vehicle. Some have a lot more tire load capacity than others.
For example I will use my 2012 Escape. The stock tires have a 104 load rating. That equals a 1984 pound capacity at 35 psi. Stock psi is 32 which equals 1885 pound capacity. A reduction of 99 pounds per tire.
The Escape weighs just under 3400 pounds with a 60/40 weight distribution. Which equals 1360 pounds on the rear tires and 2040 on the front tires. So each rear tire is carrying 680 pounds and each front tire is carrying 1020 pounds.
This may be true if the vehicle is sitting put. However, when in motion, load is not static. It constantly varies as you turn, brake, and accelerate, and so in certain cases it can be higher than what the above math would suggest.
I have several Pencil Style hand gauges and ONE Digital gauge. They're all pretty close and within +/- 1 PSI. Sounds like a lot so, I'm in the middle and really going by the butt dyno!
Don't forget about this tidbit either...I meant to mention this earlier. It is from the same document that I linked to previously.
Quote:
P-Metric or Hard Metric Tires on Light Trucks
When a P-metric or metric tire is installed on a light truck (SUV, pickup, minivan), the load capacity of the
tire is reduced by a factor of 1.1 as prescribed by the Federal Motor Vehicle Safety Standards (FMVSS).
For example, 305/50R20 has a maximum load capacity of 3086 lbs. If this tire is fitted to a light truck,
then the actual allowable load capacity for the tire is 2805 lbs. (3086 lbs. divided by 1.1).
Quote:
P-Metric or Hard Metric Tires on Light Trucks
When a P-metric or metric tire is installed on a light truck (SUV, pickup, minivan), the load capacity of the
tire is reduced by a factor of 1.1 as prescribed by the Federal Motor Vehicle Safety Standards (FMVSS).
For example, 305/50R20 has a maximum load capacity of 3086 lbs. If this tire is fitted to a light truck,
then the actual allowable load capacity for the tire is 2805 lbs. (3086 lbs. divided by 1.1).
Originally Posted By: DemoFly
Higher PSI in tires to get more MPG is false economy, unless your tires costs less than ~$40 a tire or you drive less than 2,000 miles a year.
Define "higher".
I run my Corolla tires 5 PSI higher than door jamb. 55K miles on my >$100 ea Michelins and still have more than half the tread depth left.
Higher PSI in tires to get more MPG is false economy, unless your tires costs less than ~$40 a tire or you drive less than 2,000 miles a year.
Define "higher".
I run my Corolla tires 5 PSI higher than door jamb. 55K miles on my >$100 ea Michelins and still have more than half the tread depth left.
Originally Posted By: DemoFly
Higher PSI in tires to get more MPG is false economy, unless your tires costs less than ~$40 a tire or you drive less than 2,000 miles a year.
What? Higher tire pressure (within common sense limits) usually results in lower tread wear.
Higher PSI in tires to get more MPG is false economy, unless your tires costs less than ~$40 a tire or you drive less than 2,000 miles a year.
What? Higher tire pressure (within common sense limits) usually results in lower tread wear.
where is this guy when we need him?
Originally Posted By: leeharvey418
Originally Posted By: ZachMcgowan
This is the reason why I decided to buy a Digital Tire Gauge from Mountaincrest a month ago because of some big fluctuations in my TPMS. Just making sure everything is working out well while I'm driving off to some great distances.
Wow, Zach... you sure do like your Mountaincrest Digital Tire Gauge.
All you need is a (I won't repeat it again!)...
Originally Posted By: leeharvey418
Originally Posted By: ZachMcgowan
This is the reason why I decided to buy a Digital Tire Gauge from Mountaincrest a month ago because of some big fluctuations in my TPMS. Just making sure everything is working out well while I'm driving off to some great distances.
Wow, Zach... you sure do like your Mountaincrest Digital Tire Gauge.
All you need is a (I won't repeat it again!)...
Nick1994
$100 site donor 2024
I don't really notice a ride difference with the recommended tire pressure and at 40 psi so I pump them up to 40 psi. This way I don't have to worry about the tire pressure too much, if I go a few months without checking it's not a big deal because it's still well within specs
Originally Posted By: HangFire
Originally Posted By: DemoFly
Higher PSI in tires to get more MPG is false economy, unless your tires costs less than ~$40 a tire or you drive less than 2,000 miles a year.
Define "higher".
I run my Corolla tires 5 PSI higher than door jamb. 55K miles on my >$100 ea Michelins and still have more than half the tread depth left.
By higher, I mean enough to cause increased center wear and a dangerously smaller tread patch.
My door jamb says 35 and I inflate to 38. That gives me the most improvement in MPG I can attain without sacrificing even treadwear.
That said, the amount of fuel I save is not enough, nor will it ever be enough to counteract the expense of new tires.
Originally Posted By: DemoFly
Higher PSI in tires to get more MPG is false economy, unless your tires costs less than ~$40 a tire or you drive less than 2,000 miles a year.
Define "higher".
I run my Corolla tires 5 PSI higher than door jamb. 55K miles on my >$100 ea Michelins and still have more than half the tread depth left.
By higher, I mean enough to cause increased center wear and a dangerously smaller tread patch.
My door jamb says 35 and I inflate to 38. That gives me the most improvement in MPG I can attain without sacrificing even treadwear.
That said, the amount of fuel I save is not enough, nor will it ever be enough to counteract the expense of new tires.
Every time I run anything significantly over the door placard I get too much center wear on my tires. So I stopped doing it.
I run the door placard pressure or maybe two PSI over, never more than that.
I run the door placard pressure or maybe two PSI over, never more than that.
Yeah, I typically don't change much between the door place card info and my actual readings(UP/DOWN). In this case with the car/tires(mazda3/Pirelli P7), I am dropping the rear tires down a bit more, as there is just no weight in the trunk except the space saver spare and a tank of gas.
The tires will only be at this PSI til I swap out to the winter tires. The tires will probably drop to a lower PSI due to the temp changes also but, we'll keep an eye on them.
The tires will only be at this PSI til I swap out to the winter tires. The tires will probably drop to a lower PSI due to the temp changes also but, we'll keep an eye on them.
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My Jetta called for 32/29psi but I often ran 40psi with Conti's and got nice even wear. Same size tire but in Nokian entyre suffered very fast wear at 40psi so I had to drop back to 32.
IIRC 40psi in Nordman 2 snow tires made for an ill-handling car.
Right now I'm not sure what to run with these RT43's; I have them at 32psi and it feels like I'm driving a marshmellow. Rides a bit better than the entyres but a fast steering makes me think the car is apt to oversteer now. mpg is also down considerably, but they are new tires after all.
IIRC 40psi in Nordman 2 snow tires made for an ill-handling car.
Right now I'm not sure what to run with these RT43's; I have them at 32psi and it feels like I'm driving a marshmellow. Rides a bit better than the entyres but a fast steering makes me think the car is apt to oversteer now. mpg is also down considerably, but they are new tires after all.
Originally Posted By: Char Baby
How much PSI, Up or Down can we run in our tires without hurting their structure? For example, I like a bit more PSI in the front and either, even or less PSI in the rear.
In other words, if my door jamb label says...F:30/R:30 but for ride comfort I like...F:32/R:29, is this OK?
Or, any combination of there or about!
Another example is, I have a vehicle that states on the door jamb label...F:32/R:32 but, I like, F:30/R:28...Is this OK as well?
I think you should use the placard pressures as stated. If you are unhappy with that, then change the tires to something you do like.
But at the very least, I would not use less than what is stated on the placard. And I wouldn't recommend going higher than 5 psi over the placard
Please note: All this assumes you are using the same size as listed on the vehicle tire placard.
Originally Posted By: mattwithcats
.........Remember the Ford Explorer?
Dealers were told to put a new door sticker on, original had recommended pressure too low, tires failed, vehicle rolled....
Sorry, but the inflation pressure was not what caused the tires to fail. I know this doesn't support my argument above, but here's my take on the whole Ford/Firestone issue:
Barry's Tire Tech - The Ford / Firestone Controversy
***********************************
And lastly. I am NOT a fan of using the chalk test. Not only does it assume that the tread profile is optimal at the optimal pressure (not a really good assumption), but there are so many variables that it would take many readings under many different conditions to get a good basis. Besides, the tread profile of radial tires is relatively insenstive to changes in pressure - as shown here:
How much PSI, Up or Down can we run in our tires without hurting their structure? For example, I like a bit more PSI in the front and either, even or less PSI in the rear.
In other words, if my door jamb label says...F:30/R:30 but for ride comfort I like...F:32/R:29, is this OK?
Or, any combination of there or about!
Another example is, I have a vehicle that states on the door jamb label...F:32/R:32 but, I like, F:30/R:28...Is this OK as well?
I think you should use the placard pressures as stated. If you are unhappy with that, then change the tires to something you do like.
But at the very least, I would not use less than what is stated on the placard. And I wouldn't recommend going higher than 5 psi over the placard
Please note: All this assumes you are using the same size as listed on the vehicle tire placard.
Originally Posted By: mattwithcats
.........Remember the Ford Explorer?
Dealers were told to put a new door sticker on, original had recommended pressure too low, tires failed, vehicle rolled....
Sorry, but the inflation pressure was not what caused the tires to fail. I know this doesn't support my argument above, but here's my take on the whole Ford/Firestone issue:
Barry's Tire Tech - The Ford / Firestone Controversy
***********************************
And lastly. I am NOT a fan of using the chalk test. Not only does it assume that the tread profile is optimal at the optimal pressure (not a really good assumption), but there are so many variables that it would take many readings under many different conditions to get a good basis. Besides, the tread profile of radial tires is relatively insenstive to changes in pressure - as shown here:
Well, I will keep playing with the tires PSI! I believe that Mazda's recommendation is a bit aggressive in it's tire PSI and alignment spec for Camber. The PSI, I have control of, the Camber I do not!
Once again, the tire place card is, F:32/R:32
With the Hankook Optimo H727's, I kept the tires at...F:33/R:31 and could have gone a bit higher w/o the harshness. I probably won't be getting rid of the Pirelli P7 Cint A/S+, as I don't really think that they alone are the blame.
The NEW P7's are very smooth & quiet on all pavement surfaces. Their bump absorption just isn't what I think they should they should be but too, this car('06 mazda3) isn't know for it's quiet and isolation either!
The tires are 205-55-16. So, I blame the "55", the 115K miles on the car, & the new Shocks/Struts. And maybe other factors as well such as just plane age...9 yrs old!
So, this is something I may have to adjust while running these tires. This car has been running "T" speed rated tires even though "H" is what is recommended.
Once again, the tire place card is, F:32/R:32
With the Hankook Optimo H727's, I kept the tires at...F:33/R:31 and could have gone a bit higher w/o the harshness. I probably won't be getting rid of the Pirelli P7 Cint A/S+, as I don't really think that they alone are the blame.
The NEW P7's are very smooth & quiet on all pavement surfaces. Their bump absorption just isn't what I think they should they should be but too, this car('06 mazda3) isn't know for it's quiet and isolation either!
The tires are 205-55-16. So, I blame the "55", the 115K miles on the car, & the new Shocks/Struts. And maybe other factors as well such as just plane age...9 yrs old!
So, this is something I may have to adjust while running these tires. This car has been running "T" speed rated tires even though "H" is what is recommended.
Originally Posted By: Vikas
how many of you are able to measure the air pressure in the tire without losing *any* air in the process? which is another way of asking the question as to how repeatable and how accurate are your measurements?
Good point. When I fill mine up, I go about a pound over, then check with the pencil gauge and adjust the psi down.
how many of you are able to measure the air pressure in the tire without losing *any* air in the process? which is another way of asking the question as to how repeatable and how accurate are your measurements?
Good point. When I fill mine up, I go about a pound over, then check with the pencil gauge and adjust the psi down.
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