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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 |
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#2
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Got a question for someone who lnow about auto tires out there..
"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). |
#3
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Got a question for someone who lnow about auto tires out there..
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. |
#4
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Got a question for someone who lnow about auto tires out there..
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 |
#5
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Got a question for someone who lnow about auto tires out there..
"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® |
#6
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Got a question for someone who lnow about auto tires out there..
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® > |
#7
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Got a question for someone who lnow about auto tires out there..
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. |
#8
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Got a question for someone who lnow about auto tires out there..
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 |
#9
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Got a question for someone who lnow about auto tires out there..
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. .. |
#10
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Got a question for someone who lnow about auto tires out there..
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 |
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