Vehicle Manufacturers Tire Pressure Recommendation

BlueOvalFitter

BlueOvalFitter

Joined
Feb 28, 2003
Messages
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Location
Cajun Country, La.
As most of you know, there is a recommendation on the drivers side door pillar, and in the owners manual, stating the recommended tire pressure.
My 07 F150 regular cab truck recommends 38 psi. When the tires have had 38 psi in them the ride was so rough that if I were to run over a dime I could tell if it were heads or tails. So, I run 35 psi in them. There is no uneven tire wear so I must have found the correct psi (to please me anyway).
How many of you are in the same situation as me? Do you follow what's recommended, or something close to it?
I know there are quite a bit of variables. Like, the correct/recommended psi for loaded trucks, pulling trailers, campers, boats, etc.
 
My Mazda 3 recommends 36psi front and rear up to three passengers. Full load 41 psi in the front and 46 psi in the rear. I have to admit with no load 36 in the rear is a little firm for my liking. Got it back from the dealer once and it felt horrible and it up to 48 psi. Either someones gauge is wrong but It drove like a Pogo stick. 36 is the front and 34 in the rear for me for most days.
I tend to think the high OEM specs has a little to do with fuel economy and a little with handling. They were not the normal specification when I was younger. They tended to be 32 psi (ish).
 
The pressure may be 38 to be safe for when your truck bed is loaded to capacity weight. Driving empty allows a bit less pressure for comfort. I had a 1993 Dakota with the extra load package and it road rough with it’s D rated truck tires.
 
ammolab said:
The pressure may be 38 to be safe for when your truck bed is loaded to capacity weight. Driving empty allows a bit less pressure for comfort. I had a 1993 Dakota with the extra load package and it road rough with it’s D rated truck tires.
Click to expand...
I was thinking the same thing. ;)
 
PetoOz said:
My Mazda 3 recommends 36psi front and rear up to three passengers. Full load 41 psi in the front and 46 psi in the rear. I have to admit with no load 36 in the rear is a little firm for my liking. Got it back from the dealer once and it felt horrible and it up to 48 psi. Either someones gauge is wrong but It drove like a Pogo stick. 36 is the front and 34 in the rear for me for most days.
I tend to think the high OEM specs has a little to do with fuel economy and a little with handling. They were not the normal specification when I was younger. They tended to be 32 psi (ish).
Click to expand...
LOL! :ROFLMAO: That's similar to what mine rode like with 38 psi in the tires. Like I said, I cou;d run over a dime and tell if it were heads or tails.
 
Words of Warning!

First, I consider the pressure listed on the Vehicle Tire Placard to be a specification, not a recommendation - much like the oil viscosity. This is not something the manufacturer specified lightly.

Second, the exact make and model of tire can affect the ride harshness, so consider that when buying tires.

Third, as was pointed out above, inflation pressure correlates with load carrying capacity, so if you are going to load up your vehicle, make sure the tire are inflated appropriately

And last, sometimes the inflation spec is for handling reasons. I don't think you can know if that is the case without going through the math.

So be careful and if you are going to use less pressure than the placard, do so with your eyes wide open.
 
I use the recommended PSI as a guideline. If I like the way the vehicle rides/handles, I'll keep it there.
However most of the time my vehicles are only driven with just me or wife & I. And mostly in the rear, the PSI is too high for our liking for normal driving. I may decrease the pressure by 2 PSI while keeping the front as spec'd.

When I play(usually decreasing)with the tire PSI, I only adjust by 1-2 PSI. And then back up to spec(or more) for road trips where we have lots of luggage and/or passengers.
 
I've had a couple cars which specified 30-32 psi, but that produced "underinflated" tire wear, so I upped it to 35 and that fixed it. The new car says 36, so probably I can just stick to that.
Years ago, I drove a 15 passenger van for a trip and thought I'd check the tires before leaving. The rears were half what they were supposed to be! Spent a lot of quarters airing that thing up
 
Kira said:
You'll have to forgive me.
Trucks running 38psi vs 35psi creates an appreciable difference in ride? You're joking, right?
...and people tell me I'm a delicate flower.

I suppose it's like the "tire noise" I'm incapable of hearing......a blessing in disguise.
Click to expand...
No, I'm not joking AT ALL! I have driven this truck for almost 14 years and I know it very well. You think I would start a thread if I weren't serious? :rolleyes:
And, different tires make different noises. A well made touring tire makes less road noise then a cheaper one. When I was younger I worked in my uncles tire store. He also owned a full service gas station. I sure learned A LOT about tires.
 
PetoOz said:
My Mazda 3 recommends 36psi front and rear up to three passengers. Full load 41 psi in the front and 46 psi in the rear. I have to admit with no load 36 in the rear is a little firm for my liking. Got it back from the dealer once and it felt horrible and it up to 48 psi. Either someones gauge is wrong but It drove like a Pogo stick. 36 is the front and 34 in the rear for me for most days.
I tend to think the high OEM specs has a little to do with fuel economy and a little with handling. They were not the normal specification when I was younger. They tended to be 32 psi (ish).
Click to expand...
My Audi requires 36 front 32 rear. This helps counteract the fact that the Quattro system requires the entire engine is in front of the axle and the firmer front pressure helps with the understeer
 
Kira said:
You'll have to forgive me.
Trucks running 38psi vs 35psi creates an appreciable difference in ride? You're joking, right?
...and people tell me I'm a delicate flower.

I suppose it's like the "tire noise" I'm incapable of hearing......a blessing in disguise.
Click to expand...
On my 12 F150 I can tell no difference in ride harshness between 35, 40 or 45 psi. I'm also running ten ply tires though, I feel like it rides well for a truck. I could tell a difference in 35 and 45 psi on my short bed GMC truck I had a few years back, I suspect the shorter wheel base had a lot to do with that.
 
cb_13 said:
On my 12 F150 I can tell no difference in ride harshness between 35, 40 or 45 psi. I'm also running ten ply tires though, I feel like it rides well for a truck. I could tell a difference in 35 and 45 psi on my short bed GMC truck I had a few years back, I suspect the shorter wheel base had a lot to do with that.
Click to expand...
My F150 is a regular cab SWB XL model. Even with the new (within the last 2 years) Monroe front struts and the Monroe rear shocks, it still beats me to death on not so good roads. On nice smooth roads it rides as smooth as silk.
 
If you can produce specifications of car and tires for me, I can calculate a safe pressure.

Need from car, best weighed axle( end) loads in the loading you drive with, but in lack of that empty weight, number of persons ( and weight) and load generally driven with. GAwr's and GVWR.
Maximum speed you use, and wont go over for even a minute.

From tires next:
1 maximum load or loadindex.
2 kind of tire ( standard load or XL/ reinforced/ extraload, or LT with loadrange)
3. Lessimportant speedcode.

I realise this is dangerous, but if my calc gives for instance 25 psi the 35 would certainly gives discomfort and bad gripp.

So let me calculate, to get wiser.
 
jadatis said:
If you can produce specifications of car and tires for me, I can calculate a safe pressure.

Need from car, best weighed axle( end) loads in the loading you drive with, but in lack of that empty weight, number of persons ( and weight) and load generally driven with. GAwr's and GVWR.
Maximum speed you use, and wont go over for even a minute.

From tires next:
1 maximum load or loadindex.
2 kind of tire ( standard load or XL/ reinforced/ extraload, or LT with loadrange)
3. Lessimportant speedcode.

I realise this is dangerous, but if my calc gives for instance 25 psi the 35 would certainly gives discomfort and bad gripp.

So let me calculate, to get wiser.
Click to expand...
Do you have load tables?
 
I usually run 3-5 psi over the door placard. The tires always seem to wear more even that way. My Tahoe says 35 psi and I run 40 psi. Same with my wife's Mustang.

The exception is the drag car, but it's not a street driven car and is much lighter. Max pressure on the front tires is 60 psi and that's what I run. The rear tires is 44 psi, and I run 30 psi currently. I want to increase that pressure if I can get the tires to hook at higher pressure.
 
The Critic said:
Do you have load tables?
Click to expand...
I can find some pressure/ loadcapacity lists, but I got hold of the official european calculation , end 2007, and went running with it. Now use my own determined calculation, wich comes closer to the ever to be constructed ideal formula, to my conclusions. So I dont need the " load tables" as you call them.

But if you give the asked data, I will give a full report, and show how I came to it.
If you are personally interested, send a mail to my hotmail.com adress with username jadatis ( combine yourselves, spamm- machines cant this way)
 
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