While my car was having issues, & being worked on (sitting) over the winter, two of the tires got low on pressure. Now that the car is running, I drove it to air it up, & I'm not 100% sure what psi the tires should be. I have the honey comb rims, & I know it's vague, but I have Goodyear tires. They are labeled 44 psi max. So I aired all four to 32 pounds, but I'd rather not have bad ware on the tires if this amount is too much.

The door tag on my 87 GT says 30 psi front and back. I think 32 psi will do just fine. I usually have 32-34 psi in mine.

Didn't think to check the door tag :P

Thank you!

This topic makes me wonder if the tire pressure should change for lower profile tires?

You can rub chalk (kids sidewalk stuff will do) on your tires and drive around the block.....look for even wear across the treads. If there is wear down the middle you have too much pressure. Wear on the outside?....add some air.

The pressure at which you get the most traction, most MPG, and least wear, is the proper/ideal tire pressure.

I get outstanding wear, good handling with 40-42 pnds in all my cars. I easily get 125,000 miles on a set of tires, usually more. I get no shoulder wear. Tires wear evenly across the tread. I also get excellent gas mileage in everything. My Sebring V6 conv for example gets between 32-36 mpg highway. Ive never noticed the ride suffering either. I do the same from the Sebring to a Caddy limo and a conversion van. 04 Sebring has 100K on original tires (they still look new), 95 van has 135,000 on original tires (weather cracking), caddy had 160,000 on originals, and Id just replaced two when i sold it. My Ferrari kit (Fiero) had over 100,000 on its Dunlops when I sold it and still looked nearly new.

quote Originally posted by rogergarrison: I get outstanding wear, good handling with 40-42 pnds in all my cars. I easily get 125,000 miles on a set of tires, usually more. I get no shoulder wear. Tires wear evenly across the tread. I also get excellent gas mileage in everything. My Sebring V6 conv for example gets between 32-36 mpg highway. Ive never noticed the ride suffering either. I do the same from the Sebring to a Caddy limo and a conversion van. 04 Sebring has 100K on original tires (they still look new), 95 van has 135,000 on original tires (weather cracking), caddy had 160,000 on originals, and Id just replaced two when i sold it. My Ferrari kit (Fiero) had over 100,000 on its Dunlops when I sold it and still looked nearly new.

Are the roads you're driving on softer than the compound of your tires? I can't think of any other explanation without defying physics.

Actually, there is one more. It involves raising the drive wheels off the ground.

quote Originally posted by dobey: The pressure at which you get the most traction, most MPG, and least wear, is the proper/ideal tire pressure.

Yep, different tires often wear differently and the recommended tire pressure in the door is more a happy medium than an ideal pressure, that's purported to be part of the reason the Ford Explorer got in trouble with the Firestone tires some years ago, low pressure for a more comfortable ride resulted in frictional stress, heat build up and failure since TPMS was not widely available and many owners did not routinely check tire pressure. Some tires will wear on both shoulders at vehicle spec tire pressure and give the impression they've been run low on air and not properly maintained voiding your warranty so a tuning approach is probably the best approach here.

Manufacturers recommend lower pressure to make their cars ride nice and soft.

My tires not wearing out as fast dont defy anything. To exaggerate it for testing, put 15 pnds in all the tires and push your car. Now put 40 in and push it. Lot easier isnt it ? My tires stay upright to during cornering, lot less edges scuffing and sidewalls rolling over. Pretty much like a low profile tire. My tires on the ones I have now are all OEM tires that came on them from the factory. The Sebring even has the 'junk' Continental Touring tires. I will say most of my driving is freeway.

I can back it up, you can come check the cars in person. If they dont have 75% or more percent of tread left or my gas mileage isnt what I say, Ill give you the car and title. Put up or shut up.

I run my tires near max pressure, the load carrying capacity of the tire varies with the pressure, in order for the tire to meet its max load carrying capacity it must be inflated to its max pressure is my understanding, otherwise it's not that simple as far as getting the best performance out of them as tire size also plays a role. For example, the wider the tire, the more likely it is to wear in the center if you run it near or at max pressure. It will still roll easier but it will not be of much use for wet weather when traction under normal driving conditions at speed is critical. It's a system of give and take and you need to adjust accordingly, like reading spark plugs.

[This message has been edited by Joseph Upson (edited 04-22-2013).]

I dont run wider than OEM tires. Just from looking, my tires are running with the tread planted flat all the way across. I do know if you have wider tires than intended the centers will bulge out wearing out the center first. The more the tire rolls over with lower pressure, the more wear on the shoulders (edges). Since my tires are flat on the road, I have no problem in the rain. If a tire is inflated to where the tread is flat, the pressure in the tire has no relation to how it goes thru rain. Higher inflation dont make the rubber in the tread harder, or the grooves less likely to shed the water...it just makes the cross section of the tire more rigid. A foam tire or a hard solid rubber tire with the same tread pattern and compound will drive exactly the same in the rain.

quote Originally posted by no2pencil: Didn't think to check the door tag :P

That is the place to start. Even if you experiment a lot, I believe you will find that the optimum pressure for your car will be within a couple of psi of that value.

FWIW, the "maximum pressure" rating on the sidewall of a tire is appropriate only when the tire is loaded to its maximum rated carrying capacity. It makes no sense to inflate a tire to its rated "maximum pressure" when it is more lightly loaded, but it's your car and you can do whatever you choose with it.

quote Originally posted by rogergarrison: I get outstanding wear, good handling with 40-42 pnds in all my cars. I easily get 125,000 miles on a set of tires, usually more. I get no shoulder wear. Tires wear evenly across the tread. I also get excellent gas mileage in everything. My Sebring V6 conv for example gets between 32-36 mpg highway. Ive never noticed the ride suffering either. I do the same from the Sebring to a Caddy limo and a conversion van. 04 Sebring has 100K on original tires (they still look new), 95 van has 135,000 on original tires (weather cracking), caddy had 160,000 on originals, and Id just replaced two when i sold it. My Ferrari kit (Fiero) had over 100,000 on its Dunlops when I sold it and still looked nearly new.

First, talking about what you do with other cars other than Fieros is irrelevent. Every car has a different optimal tire pressure based on weight and weight distribution.

Second, hye_4_life isn't the only one who doesn't believe you got 100,000 miles on a set of tires at 40-42 psi on your Ferrari kit, and that they had even wear and still looked like new, not to mention your other equally exaggerated claims.

quote Originally posted by rogergarrison: I can back it up, you can come check the cars in person. If they dont have 75% or more percent of tread left or my gas mileage isnt what I say, Ill give you the car and title. Put up or shut up.

You can't prove any of your statements whatsoever. You don't have the car anymore, and even if you did you wouldn't be able to prove what pressures you've been using for the past two decades (since 1995), nor that the tires are the original ones. No one has to "Put up or shut up" when outrageous and unsubstantiated claims are made which mislead others.

On the other hand, tires have been proven to obey the laws of physics: overinflate them and they balloon outwards in the center of the tire contact patch and wear out in the middle; underinflate them and they become concave in the center of the tire contact patch and wear out on the sides. Do either and you lose optimal traction since you reduce the surface area of the contact patch whether it's wet or dry. Overinflating does give better fuel ecomony due to reduced rolling friction, but it comes at the cost of tire wear.

quote Originally posted by Marvin McInnis: FWIW, the "maximum pressure" rating on the sidewall of a tire is appropriate only when the tire is loaded to its maximum rated carrying capacity. It makes no sense to inflate a tire to its rated "maximum pressure" when it is more lightly loaded, but it's your car and you can do whatever you choose with it.

It does reduce rolling resistance, and gives a slight increase in MPG. However, it may also increase wear across the center of the tread, depending on alignment, and driving habits. If the outer portions of the tread are worn down a bit more than the center, then running the pressure up higher will increase wear in the center, and help balance out the tread wear.

If you want to be "exact" you can do a fair bit of measurement and math, to come up with the absolute correct tire pressure, for the specific tires on a car, and its average load. The best thing to do is check them often, watch the wear pattern, and your fuel economy, and adjust tire pressure accordingly. Just the same as checking the oil directly is a much better indicator of when it needs to be changed, than the mileage counter, or oil wear gauge on new cars, is.

Is it true that if you fill the tire to max pressure before driving, then go out and drive and brake hard in hot conditions the tire runs a higher risk of bursting because the pressure goes up as it gets hot?

The pressure does increase as you drive, that's why the tire pressures should be measured cold. The risk of bursting because of a build up of pressure is pretty much negligible because tires almost certainly have a safety factor of at least 1.5 meaning that they could be over-inflated by as much as 1.5 times the max rated pressure before blowing off the bead or through the sidewall. Since the typical increase in pressure from cold to hot is only a couple psi, you'd have to be running pressures significantly above the max rated pressure in the first place to get it to burst with over-pressure.

The reason most tires blow is due to under-inflation. With under-inflation, the sidewalls flex and bulge out at the road level every time the wheel turns. The friction caused by the tire sidewall constantly flexing as it nears the road, and unflexing as it travels the rest of the way around the wheel is what builds up the heat in the tire. The heat is what ultimately causes the rubber to fail.

[This message has been edited by Bloozberry (edited 04-22-2013).]

Lets stick to one. I bought my new 04 Sebring. It has 100,777 miles in that roughly 10 years. These are the original tires that have never been rotated or changed, except to put them on new wheels with same dimensions several years ago. They always have had 40 pnds because thats what I run. There is no unusual wear in the center or edges. I figure theyre good for another 50,000 based on current wear. There is no doubt about the 32-36 mpg. I can prove it at any time. Not everyone trashes on their tires doing burnouts or drifting. Ive owned it since new so the tires are the ones out of the showroom unless the tire angel snuck in some nite and put new ones on it for me while i was alsleep. Ive run 40 pnds in all my cars for 30 years so thats not a doubt to me either. Now inform me what benefit it is for me to lie about it.

The only car Ive ever bought more than one set of tires for was a Mercedes I put 250,000 miles on over 12 years. I sold it with the second set still in good condition.

front


rear


front close to tread


odom read

[This message has been edited by rogergarrison (edited 04-22-2013).]

quote Originally posted by rogergarrison: 04 Sebring has 100K on original tires (they still look new),

quote Originally posted by rogergarrison:

That is hardly a new looking tire. The tread wear indicators look to be 1/8" to 1/16th from being level with the tread blocks. It also appears from the photo to have less tread in the middle and inside than on the outside blocks.

The point here is that you're saying your own personal experience with two or three tire brands on two or three different cars supports your theory that the OP should fill the tires on his Fiero to between 40-42 psi regardless what the OEM recommended tire pressures are. If it were so simple, don't you think the manufacturers of all new cars would have their tire pressures set to 40-42 psi if for no other reason than to increase their corporate average fuel economy?

quote Originally posted by Bloozberry: If it were so simple, don't you think the manufacturers of all new cars would have their tire pressures set to 40-42 psi if for no other reason than to increase their corporate average fuel economy?

They don't? The Cruze Eco I had, came with the tires inflated to 42 PSI, off the lot. Brand new car with 7 miles on it when I leased it. I'm sure tire pressure is one way they "cheat" to get by on CAFE.

But that's really beside the point here. There are a LOT of things that can affect tire wear over the life of the tire. Even with the same car, same tires, and same driving habits, simply being in a different area will affect wear. Smooth, even pavement will be much easier on a tire than an area rife with potholes, or even on ridged roadways.

Read above, they recommend lower pressure to make for a nicer ride. They dont care how long your tires last. Run on 10 pnds if you want, just saying what works for me on every car Ive had...so its no fluke. The depth of my tires are 3/16" to the top of the wear indicator. Brand new Continental tire is 1/4" so Ive got 3/4ths of my tread left. I didnt say they werent showing some wear. They are worn the same depth from one edge of the tread across to the other. The center is just as deep as the edges. The rear dont look as good because there in the dark garage and have dirt on them, but they are just as deep...so yes they look practically new. Send someone you know locally over to look at them. You can do your 30 pnds and wear out your tires in 45K if you want. I like getting 2-3 times that. It works for me, so not worth keeping up a useless debate. I never ever rotate tires either and I never need to rebalance them before theyre worn out.

quote Originally posted by rogergarrison: Lets stick to one. I bought my new 04 Sebring. It has 100,777 miles in that roughly 10 years. These are the original tires that have never been rotated or changed, except to put them on new wheels with same dimensions several years ago. They always have had 40 pnds because thats what I run. There is no unusual wear in the center or edges. I figure theyre good for another 50,000 based on current wear. There is no doubt about the 32-36 mpg. I can prove it at any time. Not everyone trashes on their tires doing burnouts or drifting. Ive owned it since new so the tires are the ones out of the showroom unless the tire angel snuck in some nite and put new ones on it for me while i was alsleep. Ive run 40 pnds in all my cars for 30 years so thats not a doubt to me either. Now inform me what benefit it is for me to lie about it. The only car Ive ever bought more than one set of tires for was a Mercedes I put 250,000 miles on over 12 years. I sold it with the second set still in good condition. front rear front close to tread odom read

I love pictures! I don't have much time at the moment but can I request three more? That should be all that's needed for a definitive conclusion to this. If this evidence proves me wrong, I will happily acknowledge it and will likely adopt your ways; if it proves you wrong, you can keep your car. We can continue with your Sebring since you have access to it. Can you please take a picture of the model of your tires? On both sides of your tires, there will be "DOT" molded into the sidewall with a series of numbers and letters following it; one side will have 7-8 characters and the other will have 10-12 characters. Can I get a picture of the 10-12 characters please? And lastly, there should be a placard in the driver's door jamb with the VIN on it. I don't care for the VIN so please feel free to white that out if you wish; my concern is the production date that should also be printed on that placard. Hopefully that placard hasn't been conveniently removed due to some accident or a modification to make the door jamb "cleaner." Blooz probably knows where I'm going with this.

Whos truth ? I have the car and it has the tires. If the tire is running flat on the pavement and there is no center wear, the tire wears evenly across as it is on my car. The contact patch is the same now as it was 10 years ago. Its not overinflation if the tire tread is flat on the road. If you have a narrower rim than the tire calls for, or you do over inflate it to say 60 pnds, then yes the center will be bulged out. On the correct rim, 5-10 pnds is not going to do it at all.

quote Originally posted by rogergarrison: I set my tires after Ive driven it.

Wait a minute..... So you're saying that you check and adjust your tire pressure after you have heated up the tires by driving?

quote Originally posted by no2pencil: While my car was having issues, & being worked on (sitting) over the winter, two of the tires got low on pressure. Now that the car is running, I drove it to air it up, & I'm not 100% sure what psi the tires should be. I have the honey comb rims, & I know it's vague, but I have Goodyear tires. They are labeled 44 psi max. So I aired all four to 32 pounds, but I'd rather not have bad ware on the tires if this amount is too much.

see https://www.fiero.nl/forum/F...HTML/127964.html#p13

quote Originally posted by rogergarrison: I get outstanding wear, good handling with 40-42 pnds in all my cars. I easily get 125,000 miles on a set of tires, usually more. I get no shoulder wear. .... 04 Sebring has 100K on original tires (they still look new)

100,000 miles and on Tire w/ 60-80,000 wear warranty? (H 60,000, S & T 80,000 I can't read the speed ratings in front picture.)
Sorry... Just means Tread Compound is very hard. Typical in tires w/ high tread wear...


Over/under inflation vs Wear pattern often means little for tires built in last 2 decades, maybe more... about when all cars moved to Steel/Aramid Belted Radials. Do Not trust traditional wear pattern for inflation problems.
Too low tire can blow before wear is a issue.
Too high? same thing.
Never go over Max Inflation on tire wall. Max number when COLD. This number expect some expansion when tire gets hot when running.
Too Low is more like a problem but Either can break the tread belt(s).

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

quote Originally posted by FTF Engineering: Wait a minute..... So you're saying that you check and adjust your tire pressure after you have heated up the tires by driving?

That explains why the center of his tire isn't worn more. As they cool later on, the pressure drops a few pounds.

quote Originally posted by theogre: 100,000 miles and on Tire w/ 60-80,000 wear warranty? (H 60,000, S & T 80,000 I can't read the speed ratings in front picture.) Sorry... Just means Tread Compound is very hard. Typical in tires w/ high tread wear... Over/under inflation vs Wear pattern often means little for tires built in last 2 decades, maybe more... about when all cars moved to Steel/Aramid Belted Radials. Do Not trust traditional wear pattern for inflation problems. Too low tire can blow before wear is a issue. Too high? same thing. Never go over Max Inflation on tire wall. Max number when COLD. This number expect some expansion when tire gets hot when running. Too Low is more like a problem but Either can break the tread belt(s).

Based on the tread pattern, I believe these are the Continentals he's driving on:

http://www.americastire.com...NT|pc|93611&pc=26827

They have a 60,000 mile warranty and Roger is predicting 150k+. The speed rating is H (up to 130MPH), which is completely independent of treadwear. Speed rating is a measure of a tire sustaining a rated speed for a set period of time without structural failure. I believe the indicator you're referring to is the UTQG rating which includes the manufacturer's treadwear, traction, temperature dissipation ratings. Tires will tell you everything about a car; everything about how the owner maintains/treats the car, including maintaining tire pressure.

quote Originally posted by theogre: Over/under inflation vs Wear pattern often means little for tires built in last 2 decades, maybe more... about when all cars moved to Steel/Aramid Belted Radials. Do Not trust traditional wear pattern for inflation problems.

I disagree. I store about 90 classic, antique, and special interest cars for folks in the area over the winter and see many, many tires since I top every one of them up (360 in total) in the spring to the manufacturer's suggested pressure when it's available. I try to read each of them to advise the owner what he might be doing wrong. While it's usually more apparent on wider tires, the effects of over-inflation and under-inflation are real and obvious on most steel belted radials if you care enough to look closely.

quote Originally posted by FTF Engineering: Wait a minute..... So you're saying that you check and adjust your tire pressure after you have heated up the tires by driving?

You need to check cold and warm pressures. Warm tire pressure should be 10% higher than cold. Adjust your cold pressures accordingly.

Jonathan

quote Originally posted by Boostdreamer: You need to check cold and warm pressures.

No I don't.



It's the law.

quote Originally posted by hye_4_life: Based on the tread pattern, I believe these are the Continentals he's driving on... The speed rating is H (up to 130MPH), which is completely independent of treadwear. ... I believe the indicator you're referring to is the UTQG rating...

No and Doesn't matter here. Photoshop poor pictures to read tire data... No thanks.
Speed rating affect wear warranty as I listed above from Continental's ContiProContact Warranty.PDF page 7 and from Tirerack.
205 is available in T & H and Both can have same tread compound etc but have different wear warranties because of speed rating.
Saying High Tire Pressure = Long Life? No...
In general, Long wear warranties means harder tread compound.
Getting 100,000+ miles on hard compound tires is not very hard.

quote Originally posted by rogergarrison: I set my tires after Ive driven it.

quote Originally posted by Boostdreamer: You need to check cold and warm pressures. Warm tire pressure should be 10% higher than cold. Adjust your cold pressures accordingly.

Problem is Hot temp has way too many variables... Temp of Roads you drive on that day. Distance. City/Highway. etc. etc. And Tire temp can change while running.

OE and Max is Cold temp pressure... Cold means Parked w/ enough time to cool to parking place temperature.

Tire pressure vs tire temp changes... 1PSI for every 10°F.
TireBuyer and many, many others....

quote Originally posted by Bloozberry: I disagree. ... While it's usually more apparent on wider tires, the effects of over-inflation and under-inflation are real and obvious on most steel belted radials if you care enough to look closely.

Most will simply looks at books/google pictures that often show worse case examples and think their tires look ok.

With today's hard tread compounds and tire construction... By the time wear pattern is obvious to many owners, often take months of driving or major over/under inflation to show up, most times means the tire is dead or close to dead.

Sad thing is Most time owners will drive w/ tire 5-10PSI or more under inflate. Poof? This is Why US and EU are forcing OEM to install TPMS.

Yes, Use OE Pressure when you can find the data and I've said this many times.

quote Originally posted by theogre: OE and Max is Cold temp pressure... Cold means Parked w/ enough time to cool to parking place temperature. .

Thats probably 40-80F I would guess too?
Northern climates may make a difference when ambient temps can get to -20F or colder and 100F or hotter.

quote Originally posted by Boostdreamer: Warm tire pressure should be 10% higher than cold.

Maybe. A 10% increase in pressure would require a temperature rise of ~53 degrees F, which is pretty high under normal driving conditions. See below.

Correction: A 10% increase in absolute pressure would require a temperature rise of ~53° F; a 10% increase in gauge pressure (for a nominal 30 psig tire) would require a temperature rise of only ~35° F. See below.

quote Originally posted by theogre: Tire pressure vs tire temp changes... 1PSI for every 10°F.

Close ... but not quite correct. See below.

quote Originally posted by FTF Engineering: It's the law.

Bingo! Since V, n, and R are constants in the case we're considering, the equation reduces to:

P ~ T (i.e P is directly proportional to T) ... where P is absolute pressure and T is absolute temperature (i.e. temperature above absolute zero), in degrees Kelvin (metric/SI units) or degrees Rankine (English units)

Normal ambient absolute temperature is about 295 degrees Kelvin (530 degrees Rankine), so the change in tire pressure will be about 0.34% (roughly 0.15 psi) per degree Celsius, which is about 0.19% (0.085 psi) per degree Fahrenheit.


Edit: For reference:

Absolute pressure (kPa) = gauge pressure + 100
Absolute temperature (degrees Kelvin) = degrees Celsius + 273

Absolute pressure (psi) = gauge pressure + 15
Absolute temperature (degrees Rankine) = degrees Fahrenheit + 459


Edit: To clarify absolute pressure vs. gauge pressure

[This message has been edited by Marvin McInnis (edited 07-06-2013).]

Cant wait to see the date code on those tires.

quote Originally posted by edfiero: Cant wait to see the date code on those tires.

I have looked for this date code on my tires , but cant find one .
do all tires have them ? or only new tires ? or may be they started in a certain year and older tires don't have them.
did'nt mean to change the subject but if I wait to ask I'll never remember

quote Originally posted by kendallville: I have looked for this date code on my tires , but cant find one . do all tires have them ? or only new tires ?

The date code may be on only one sidewall of the tire; depending on how it was mounted on the wheel you may have to look on the back side. On the tire pictured below the date code is 5107, meaning the 51st week of 2007:



FWIW, the date codes for tires manufactured prior to 2000 were only 3 digits. See: TireRack.com: Determining the Age of a Tire

[This message has been edited by Marvin McInnis (edited 04-25-2013).]

hard to read but here goes




186 then what looks like a circle with a - inside
the web site says a triangle for tires made in the 90s
maybe they are the original tires?
edit to add I have allways ran 40psi any thing less and the rear end wants to wander.

[This message has been edited by kendallville (edited 04-25-2013).]

quote Originally posted by kendallville: hard to read but here goes

Date code could even be 1986. Regardless, that tire should be replaced due to the extensive sidewall checking alone; failure is only a matter of time.

[This message has been edited by Marvin McInnis (edited 04-25-2013).]