Got a question for someone who lnow about auto tires out there..

Got a question for someone who lnow about auto tires out there.

I recently had to get new tires on car and when I asked the tire
person about what to keep the pressure at he said 30 PSI. When I
mentioned that the tires called for 44 PSI he said that you go by what
the vehicle calls for which is 30 PSI rather then what the tires
called for even though the tires looked soft at 30 PSI to me.

Is there anyone out there that works at an auto repair or tire place
that could offer me some insight here ?? At present I am about to
split the difference and carry the pressure at 37 PSI.

Opinion wanted. TIA

"kraut" > wrote in message
...
>
>
> Got a question for someone who lnow about auto tires out there.
>
> I recently had to get new tires on car and when I asked the tire
> person about what to keep the pressure at he said 30 PSI. When I
> mentioned that the tires called for 44 PSI he said that you go by what
> the vehicle calls for which is 30 PSI rather then what the tires
> called for even though the tires looked soft at 30 PSI to me.
>
> Is there anyone out there that works at an auto repair or tire place
> that could offer me some insight here ?? At present I am about to
> split the difference and carry the pressure at 37 PSI.
>
> Opinion wanted. TIA
>
>

As long as the tires meet OEM specs, and the vehicle is not overloaded you
should go with the manufacturer's recommended tire pressure as indicated on
the decal (usually attached to the driver's door pillar
--
Disclaimer:
Due to the nature of solving problems over the internet being mostly
guesswork,
please do not consider the above recommendations as the only possible
solutions.

--
Kevin Mouton
Automotive Technology Instructor
"If women don't find you handsome, they should at least find you handy"
Red Green).

On Sat, 5 Aug 2006 10:07:25 -0500, "Kevin" > wrote:

>
>"kraut" > wrote in message
.. .
>>
>>
>> Got a question for someone who lnow about auto tires out there.
>>
>> I recently had to get new tires on car and when I asked the tire
>> person about what to keep the pressure at he said 30 PSI.

>> When I mentioned that the tires called for 44 PSI he said that you go by what
>> the vehicle calls for

Refreshing! All too many tire store employees adamantly refuse to
adhere to the vehicle manufacturer's specs.

>> which is 30 PSI rather then what the tires
>> called for even though the tires looked soft at 30 PSI to me.

Radial tires often look a little soft.

>> Is there anyone out there that works at an auto repair or tire place
>> that could offer me some insight here ?? At present I am about to
>> split the difference and carry the pressure at 37 PSI.
>>
>> Opinion wanted. TIA
>>
>>
>
>As long as the tires meet OEM specs, and the vehicle is not overloaded you
>should go with the manufacturer's recommended tire pressure as indicated on
>the decal (usually attached to the driver's door pillar

Exactly! NOWHERE on the tire does it say what pressure is called for.
If you read the entire statement it says" xxx maximum load at xxx
maximum pressure. CONSULT PLACARD IN VEHICLE." Unless the vehicle
manufacturer badly skimped on tire size the tire typically is not
loaded anywhere close to maximum capability and does not require
maximum pressure nor is maximum pressure appropriate. While
under-inflation has obvious bad consequences, over-inflation is not a
whole lot better. It reduces contact patch area and thus compromises
handling. Over-inflated front tires can cause a vehicle to wander all
over the highway as if intoxicated due to promoting oversteer. This
has to do with the ratio of sidewall slip angles between the front and
rear tires. The handling of a vehicle is dependent on many factors
including spring rate, roll center, front/rear weight percentages etc.
etc. The vehicle manufacturer's chassis engineering department knows
all these things about a particular application. The tire
manufacturer does not know if the tire is going on the front or the
back -- often calling for different inflation pressures -- let alone
what make and model vehicle it will be mounted on. Just for one
example many FWD cars will be so front-heavy that they call for 32
front/26 rear. Then again, my 3/4 ton truck at maximum load -- which
load is imposed primarly on the rear axle -- wants 55 front/85 rear.

Rarely does a week go by where I do not succesfully address handling
and ride complaints -- often with the owner gathering estimates for
struts or shocks -- by setting the tires to the spec on the door
pillar, glove box lid or wherever.

Don
www.donsautomotive.com
>--
>Disclaimer:
>Due to the nature of solving problems over the internet being mostly
>guesswork,
>please do not consider the above recommendations as the only possible
>solutions.

On Sat, 05 Aug 2006 11:49:54 -0400, lugnut >
wrote:

>On Sat, 05 Aug 2006 14:12:56 GMT, kraut
> wrote:
>
>>
>>
>>Got a question for someone who lnow about auto tires out there.
>>
>>I recently had to get new tires on car and when I asked the tire
>>person about what to keep the pressure at he said 30 PSI. When I
>>mentioned that the tires called for 44 PSI he said that you go by what
>>the vehicle calls for which is 30 PSI rather then what the tires
>>called for even though the tires looked soft at 30 PSI to me.
>>
>>Is there anyone out there that works at an auto repair or tire place
>>that could offer me some insight here ?? At present I am about to
>>split the difference and carry the pressure at 37 PSI.
>>
>>Opinion wanted. TIA
>>
>
>
>You don't say what kind of vehicle you have. If it is a
>truck and you change the load range rating, you may need to
>use a different pressure. If you installed the original
>spec tire that came on the vehicle, you need to follow the
>vehicle manufacturer's recommendation unless you have good
>reason not to do this that may include other vehicle
>modifications. Once you leave the OEM tire specs, you are
>on your own to figure out the best pressure or foillow
>someonelse's recommendation assuming they have any basis for
>their recommendation.

Most often they do not!

don]
www.donsautomotive.com

>
>Lugnut

"Kevin" > wrote in
news:xw2Bg.67502$9c6.22628@dukeread11:

>
> "kraut" > wrote in message
> ...
>>
>>
>> Got a question for someone who lnow about auto tires out there.
>>
>> I recently had to get new tires on car and when I asked the tire
>> person about what to keep the pressure at he said 30 PSI. When I
>> mentioned that the tires called for 44 PSI he said that you go by
>> what the vehicle calls for which is 30 PSI rather then what the tires
>> called for even though the tires looked soft at 30 PSI to me.
>>
>> Is there anyone out there that works at an auto repair or tire place
>> that could offer me some insight here ?? At present I am about to
>> split the difference and carry the pressure at 37 PSI.
>>
>> Opinion wanted. TIA
>>
>>
>
> As long as the tires meet OEM specs, and the vehicle is not overloaded
> you should go with the manufacturer's recommended tire pressure as
> indicated on the decal (usually attached to the driver's door pillar



Isn't this exactly the sort of thing that got Ford in trouble with the
Explorer a few years back?


--
TeGGeR®

On Sat, 5 Aug 2006 16:52:05 +0000 (UTC), "TeGGeR®" >
wrote:

>"Kevin" > wrote in
>news:xw2Bg.67502$9c6.22628@dukeread11:
>
>>
>> "kraut" > wrote in message
>> ...
>>>
>>>
>>> Got a question for someone who lnow about auto tires out there.
>>>
>>> I recently had to get new tires on car and when I asked the tire
>>> person about what to keep the pressure at he said 30 PSI. When I
>>> mentioned that the tires called for 44 PSI he said that you go by
>>> what the vehicle calls for which is 30 PSI rather then what the tires
>>> called for even though the tires looked soft at 30 PSI to me.
>>>
>>> Is there anyone out there that works at an auto repair or tire place
>>> that could offer me some insight here ?? At present I am about to
>>> split the difference and carry the pressure at 37 PSI.
>>>
>>> Opinion wanted. TIA
>>>
>>>
>>
>> As long as the tires meet OEM specs, and the vehicle is not overloaded
>> you should go with the manufacturer's recommended tire pressure as
>> indicated on the decal (usually attached to the driver's door pillar
>
>
>
>Isn't this exactly the sort of thing that got Ford in trouble with the
>Explorer a few years back?


What happened with the Explorer is that they were a little bit skimpy
on tire capacity for the vehicle. They also had a problem with a high
center of gravity due to engine placement necessary to clear the twin
I-beam suspension. So they had a handling problems which they were
able to mimimize with relatively low tire pressures. Unfortunately
the crap Firestones couldn't take the heat. Ideal tire pressure is a
compromise involving lots of parameters. Unfortunately with the
Explorer the parameters were unworkable. Had they gone up one tire
size and used quality rubber there would have been no problem at all
with the specified 26 PSI.

Don
www.donsautomotive.com

>
>
>--
>TeGGeR®
>

ray wrote:
> Don wrote:
>
> Hey Don, what kind of tire pressure do you suggest for radials on dirt?
> All the books and all the recommendations I get are for guys running
> bias ply race tires.
>
> They're BFG Radial TA's on a heavy Camaro. Been running around 20psi,
> thinking of going down to 16-18 because that's what everyone says but
> wondering if that's too low - and like I said, they're all running bias
> ply tires in different classes than I am.
>
> Ray



always listen to what the manufacturer gave specs. for.

On Sun, 06 Aug 2006 01:35:49 GMT, ray
> wrote:

>Don wrote:
>
>Hey Don, what kind of tire pressure do you suggest for radials on dirt?

I have no clue, I have never done it. What about stagger? Can you
run different size tires on the back? I assume you are allowed a
locked rear end. Do you have a stagger gauge or can you borrow one?
I suspect -- but do not know for a fact -- that it would be harder to
adjust radial tires for stagger through air pressure. With bias ply
tires on dirt we work with what we feel is a fairly large "window" of
acceptable pressures in regard to traction and use pressures of the
rear tires to fine-tune stagger which we consider the most critical.
Front wheel stagger pretty much doesn't make a rat's ass!

Don
www.donsautomotive.com

>All the books and all the recommendations I get are for guys running
>bias ply race tires.
>
>They're BFG Radial TA's on a heavy Camaro. Been running around 20psi,
>thinking of going down to 16-18 because that's what everyone says but
>wondering if that's too low

I typically run 8-10 on my left rear!

> - and like I said, they're all running bias
>ply tires in different classes than I am.
>
>Ray

Don > wrote in article
>...
> On Sun, 06 Aug 2006 01:35:49 GMT, ray
> > wrote:
>
> >Don wrote:
> >
> >Hey Don, what kind of tire pressure do you suggest for radials on dirt?
>
> I have no clue, I have never done it. What about stagger? Can you
> run different size tires on the back? I assume you are allowed a
> locked rear end. Do you have a stagger gauge or can you borrow one?
> I suspect -- but do not know for a fact -- that it would be harder to
> adjust radial tires for stagger through air pressure. With bias ply
> tires on dirt we work with what we feel is a fairly large "window" of
> acceptable pressures in regard to traction and use pressures of the
> rear tires to fine-tune stagger which we consider the most critical.
> Front wheel stagger pretty much doesn't make a rat's ass!
>
> Don
> www.donsautomotive.com
>
> >All the books and all the recommendations I get are for guys running
> >bias ply race tires.
> >
> >They're BFG Radial TA's on a heavy Camaro. Been running around 20psi,
> >thinking of going down to 16-18 because that's what everyone says but
> >wondering if that's too low
>
> I typically run 8-10 on my left rear!
>
> > - and like I said, they're all running bias
> >ply tires in different classes than I am.
> >
> >Ray
>
>

If you run two tires with exactly equal circumferences, but the LR has that
circumference @ 15 p.s.i. and the RR has it @ 30 p.s.i., you will have a
difference in loaded radius when the tires are on the car and the car is on
the ground. THAT is stagger.

The wheels are turning about the loaded radii.

..

On Sun, 06 Aug 2006 10:03:46 -0500, "*" > wrote:

>
>
>Don > wrote in article
>...
>> On Sun, 06 Aug 2006 01:35:49 GMT, ray
>> > wrote:
>>
>> >Don wrote:
>> >
>> >Hey Don, what kind of tire pressure do you suggest for radials on dirt?
>>
>> I have no clue, I have never done it. What about stagger? Can you
>> run different size tires on the back? I assume you are allowed a
>> locked rear end. Do you have a stagger gauge or can you borrow one?
>> I suspect -- but do not know for a fact -- that it would be harder to
>> adjust radial tires for stagger through air pressure. With bias ply
>> tires on dirt we work with what we feel is a fairly large "window" of
>> acceptable pressures in regard to traction and use pressures of the
>> rear tires to fine-tune stagger which we consider the most critical.
>> Front wheel stagger pretty much doesn't make a rat's ass!
>>
>> Don
>> www.donsautomotive.com
>>
>> >All the books and all the recommendations I get are for guys running
>> >bias ply race tires.
>> >
>> >They're BFG Radial TA's on a heavy Camaro. Been running around 20psi,
>> >thinking of going down to 16-18 because that's what everyone says but
>> >wondering if that's too low
>>
>> I typically run 8-10 on my left rear!
>>
>> > - and like I said, they're all running bias
>> >ply tires in different classes than I am.
>> >
>> >Ray
>>
>>
>
>If you run two tires with exactly equal circumferences, but the LR has that
>circumference @ 15 p.s.i. and the RR has it @ 30 p.s.i., you will have a
>difference in loaded radius when the tires are on the car and the car is on
>the ground. THAT is stagger.
>
>The wheels are turning about the loaded radii.


Understood. Therefore the stagger gauge does not tell the whole
story. To complicate things further, true stagger will change with
weight transfer when cornering. I have been meaning to mark some
tires, put them on the front of my racecar and roll it forward
measuring the turns and come up with a rought formula for the
inflation factor.

Don
www.donsautomotive.com