Wore my tires out.

[benebob]

Originally posted by Porter



Your concept of how tires react to pressure is not relevant in the modern world. You're thinking of a tire as a balloon, as tires were back in the 1940s and 1950s.

Modern passenger tires do NOT dome the tread or wear excessively in the middle at any pressure under about 55-60psi.

"Popping" a tire is not something that I've ever heard of. Many times I've seen tires fail due to underinflation and excessive stress on the rubber, but never due to higher pressures.

The engineers at the Michelin Black Lake Proving Grounds (where we autocross) who test tires for a living were pleased to see that we run pressures at max or slightly higher. They *****ed and moaned for 20 minutes about how people don't run enough air pressure in their tires, and how it negatively affects both handling and tire life.


So, you're telling me that you'd continue to run 28 psi on three different sets of tires....

One with a 35psi max, one with a 44psi max, and another with 51psi max.

What would you run a 51psi max tire at? The doorjamb recommendation? The suggestion is absurd.






P.S. - "Max Pressure" is Max COLD Pressure. The tire is designed to allow pressures up to 12psi higher than that due to heat and stress.

Go on thinking what you want. Might not be correct but then again the sky really is purple (if you get up far enough at least). Its obvious your not gonna change your mind and your driving habits are probably fairly close to the conditions in which you would run close to a max PSI but daily driving is not that contition. I have a set of RE92s that have no tread in the middle from running high PSIs any tire will ballon regardless of when they were made it is just a case of how much it will.


Did commuter ask what to put your tires at when you go to the track? Tires also have a minimum PSI so if you go with the minimum PSI the tire should perform within specs right? Actually just come up here and drive on any of our highways in PA for an hour and you'll be dropping that pressure for the drive home. Any tire can balloon. No not to the same extent of the pure rubber tires from the 40s but I had a set of RE-82s that ballooned from being "over inflated" but yet they were well below the max psi.

[svx_commuter]

The tire have a max inflate of 44 psi. Rocks

Struts acn wear a few ways:
1. Oil is forced out and they don't damp and lets the car bounce up and down. Find this by pushing up and down on the car or driving over bumps.
2. The top bushing wears and the strut shaft gets play at the top of the strut. Find this pulling and pushing at the top of the tire.
3. The valves lock-up and what? If I push down on the car it won't move? How do you check this?

Nick, I have stock rims and everything is tight and the struts are okay. I am leaning toward low inflation for these tires and lack of rotation.

Originally posted by benebob


Go on thinking what you want. Might not be correct but then again the sky really is purple (if you get up far enough at least). Its obvious your not gonna change your mind and your driving habits are probably fairly close to the conditions in which you would run close to a max PSI but daily driving is not that contition. I have a set of RE92s that have no tread in the middle from running high PSIs any tire will ballon regardless of when they were made it is just a case of how much it will.


Did commuter ask what to put your tires at when you go to the track? Tires also have a minimum PSI so if you go with the minimum PSI the tire should perform within specs right? Actually just come up here and drive on any of our highways in PA for an hour and you'll be dropping that pressure for the drive home. Any tire can balloon. No not to the same extent of the pure rubber tires from the 40s but I had a set of RE-82s that ballooned from being "over inflated" but yet they were well below the max psi.

I have driven tens of thousands of miles all over the northeast, including PA. I can also lump MI, WI, IL, CO, AZ, WA, OR, CA, LA, and MO in there, among a host of others.

My tire pressures did just fine, even when the road was rough. My suspension is operating properly.... ideally the suspension is supposed to soak up road imperfections, not the tire. The tire isolates you from road surface grit, but anything larger than pea gravel should be soaked up by the suspension, not the tire. Pneumatic effect is what causes the boaty sensation... something to be eliminated at all cost.


If your tires were "doming" with less than the max pressure, I'd recommend you call Bridgestone on the phone and let them know. I've never experienced this phenomenon, and I've owned RE92s, RE930s, and RE950s.



Do your comments on this issue derive from the same sentiment that seems to be pervasive on this board, i.e. "Don't modify an SVX! It's supposed to be as soft and luxurious as possible! It's a long distance tourer, not a sports car! You speak sacrelige!"

I find it funny.


If you are running anything less than a sport oriented all-season tire on the SVX, you might want to consider getting a real set of tires. I have found the winter traction on the Potenza RE950 to be quite acceptable, even driving in the mountains in heavy snow and icy conditions.


You may want to take notice that BMW and Mercedes do not recommend 28psi... they recommend 35-40 depending on the tires, and I've never heard anyone call the ride "harsh" in a Mercedes.

Originally posted by svx_commuter
The tire have a max inflate of 44 psi. Rocks

Struts acn wear a few ways:
1. Oil is forced out and they don't damp and lets the car bounce up and down. Find this by pushing up and down on the car or driving over bumps.
2. The top bushing wears and the strut shaft gets play at the top of the strut. Find this pulling and pushing at the top of the tire.
3. The valves lock-up and what? If I push down on the car it won't move? How do you check this?

Nick, I have stock rims and everything is tight and the struts are okay. I am leaning toward low inflation for these tires and lack of rotation.

The struts will bind internally under load... this results in a *bang* effect if you hit a bump while cornering. This happens when most or all of the oil escapes and the seals get dry.

Try running pressures of 44psi front / 40psi rear. Adjust them when the tires are cold.

Seriously, experiment with it. I think you'll be amazed at how much better the car handles with proper pressures. It's night and day. You'll need to readjust your pressures according to ambient conditions... i.e. 90deg in the summer will give you different transient pressures than 30deg in the winter. Readjust to 44/40 "cold" and you should be spot on regardless of weather.

Originally posted by benebob
Did commuter ask what to put your tires at when you go to the track? Tires also have a minimum PSI so if you go with the minimum PSI the tire should perform within specs right? Actually just come up here and drive on any of our highways in PA for an hour and you'll be dropping that pressure for the drive home. Any tire can balloon. No not to the same extent of the pure rubber tires from the 40s but I had a set of RE-82s that ballooned from being "over inflated" but yet they were well below the max psi.

P.S. - When I go to the track I inflate into the 50s.

The winning stock class WRX in the region runs 48f/60r on his race tires and wins consistently over all kinds of modified vehicles.

I would run in the high 40s on a true road course.

[svx_commuter]

Originally posted by Porter



You have stiffer strut top mounts? I need a set. Where did you get them? Can I buy yours?


P.S. - If your struts keep wearing out, buy the Konis and run them on full soft (stock spring recommendation). Problem solved almost permanently.

I got the mounts from Liberty Subaru. The part number is in a file around here. service bulletin.

I find it hard to believe that the struts wear out that fast. I want a strut testing machine.

I am getting the opinion that different tire types need different pressures.

Nice of you guys to argue in my thread.

Any ideas on how to hook up a grinder to round off my tires?

John

Originally posted by Mr. Pockets


Thanks, but I guessed the sidewall explanation myself. Still, I have no evidence to support that guess, and you have still provided me with none beyond your own opinions or knowledge. I am also very interested to see more facts to support the claim that Ford's recommended pressure for the Explorer was at fault for the tread separation that caused so many accidents.

http://www.citizen.org/litigation/br...es.cfm?ID=1069

8. Also unknown is the degree to which the design of the Ford Explorer is responsible for the accidents in question. Evidence supports the conclusion that Ford Explorers are prone to roll over. In mid-1989, company engineers outlined the design modifications that could make the vehicle safer, which included widening the vehicle's track width, altering the suspension system, and lowering the vehicle's center of gravity. However, these major design changes would have taken up to ten months to implement. Rather than re-engineer the Explorer, Ford decided to lower the recommended air pressure in its Firestone tires to 26 pounds per square inch ("psi") to make the vehicle less likely to roll over when a driver swerved suddenly, left the road, or had tire failure, despite Firestone's recommendation of 35 psi for the maximum load.
9. Ford's decision to lower the tire pressure may have exacerbated the defects in Firestone tires. The lower tire pressure puts more stress on the tires, leading to the heat buildup and increasing the likelihood of tread separation. Evidence strongly suggests that Firestone model ATX, ATX II and Wilderness tires on Ford Explorers are overheating with highway use, causing the tread to separate and the Explorers to experience catastrophic crashes, not infrequently rolling over and causing fatal injuries. To date, NHTSA has documented 88 deaths and 250 injuries. Dozens of other fatalities occurred abroad.

http://www.srisd.com/CRASH_Report_Vol_3,_Issue_2.htm

Upon closer analysis of the tire defect, it appears that the defect becomes dangerous primarily as a result of tire underinflation, which results in very high forces within the wall of the tire. This finding, in fact, has prompted talk of new legislation requiring on-board tire pressure sensors which would constantly monitor the vehicle’s tire pressure and provide a read-out on the dashboard and warning signals. Low tire pressure results in increased tire wear, decreased fuel economy, poor traction and handling characteristics, and an increased likelihood of catastrophic failure or separation from the rim upon hard turns which often precipitate roll-overs in SUV-class vehicles due to their high center of gravity.

http://www.businessweek.com/smallbiz...000915_563.htm

They think underinflation -- Ford's recommendation that the tires be inflated with 26 pounds of air pressure rather than 35 pounds, as Firestone recommends -- was a factor in the fatal accidents. "Nobody in their right mind puts 26 pounds in an SUV," Borges says. "You can't underinflate a tire and hope it holds up."

http://www.citizen.org/litigation/br...es.cfm?ID=1070

Evidence supports the conclusion that Ford Explorers are prone to roll over. In mid-1989, company engineers outlined the design modifications that could make the vehicle safer, which included widening the vehicle's track width, altering the suspension system, and lowering the vehicle's center of gravity. See, e.g., Kevin Carmody, Tire Loss Deadlier On Explorers, Austin American Statesman (Aug. 25, 2000), at A1; Claybrook Aff. ¶ 9. However, these major design changes would have taken up to ten months to implement. Claybrook Aff. ¶ 9. Rather than re-engineer the Explorer, Ford decided to lower the recommended air pressure in its Firestone tires to 26 pounds per square inch ("psi") to make the vehicle less likely to roll over when a driver swerved suddenly, left the road, or experienced tire failure, despite Firestone's recommendation of 35 psi for the maximum load. Id.

Ford's decision to lower the tire pressure may have exacerbated the defects in Firestone tires. The lower tire pressure puts more stress on the tires, leading to heat buildup and increasing the likelihood of tread separation. Claybrook Aff. ¶ 10. Evidence strongly suggests that Firestone model ATX, ATX II and Wilderness tires on Ford Explorers are overheating with highway use, causing the tread to separate and the Explorers to experience catastrophic crashes, not infrequently rolling over and causing fatal injuries. Id.

Ford is seeking a protective order to cover documents that might help answer questions about the safety of its vehicle design and whether its decision to lower the tire pressure in tires on Ford Explorers increased the risk of tire failure. For instance, Ford is withholding documents on vehicle stability and vehicle design, which might determine whether the design of the Ford Explorer makes it more likely than other vehicles to roll over when a tire loses its tread.

Originally posted by svx_commuter


I got the mounts from Liberty Subaru. The part number is in a file around here. service bulletin.

I find it hard to believe that the struts wear out that fast. I want a strut testing machine.

I am getting the opinion that different tire types need different pressures.

Nice of you guys to argue in my thread.

Any ideas on how to hook up a grinder to round off my tires?

John

Ya, it's weird that your struts have worn out that fast. I'd expect them to last 60k under normal use, 40k under "spirited" conditions. I'll check into the service bulletin info, thanks for the tip! If you want to get rid of yours, let me know! I'm in the market.

[Mr. Pockets]

I searched for a little bit and found no substantial evidence that Ford's recommended tire inflation pressure had anything to do with the tread separation that caused so many accidents.

As a matter of fact, the bulk of Firestone's claims concerning the Explorer's safety focused on the car's handling after the tread separated. Firestone claimed, in a number of complaints to the NHTSA, that the Explorer was more likely to lose control and roll over after tread separation than other similar SUV models. The NHTSA's opinion was that the data available simply didn't support those claims.

I found no mention anywhere that anybody claimed that Ford's lower recommended tire pressure caused either the tread separation or the rollovers.

So, Porter, despite the fact that you have ignored my request twice now, I ask you again: what evidence do you have to support your claim that Ford's recommended tire pressure caused either the tread separation or the rollovers?

Edit:

Ha, crap, you posted some stuff while I was typing this one. Thanks, I'll look at the links you posted!

Here's more.. this one's great.

http://www.safetrip.org/press/press_..._0520_usat.php

State attorneys general, who collected $ 41.5 million to settle an investigation of Bridgestone/Firestone last November, are using part of the money starting this week to advertise the dangers of driving on underinflated tires.

The settlement included $ 5 million for tire safety education, because tire pressure figured prominently in the August 2000 recall of 6.5 million Firestone ATX, ATXII and Wilderness AT tires.

"Improper tire inflation results in thousands of accidents each year," says Tennessee Attorney General Paul Summers. Ads will run on cable and local TV and network radio in all major markets around the big summer driving weekends -- Memorial Day, July 4 and Labor Day. The TV ad compares the performance of underinflated tires with underinflated basketballs.

~~~~~~~~~

Low pressure can cause tires to overheat and fail.

Though many consumers have a basic tire gauge rattling around in their glovebox or trunk, too few actually use them. A NHTSA survey last year found that 27% of passenger cars and 32% of trucks -- minivans, pickups and SUVs -- had at least one substantially underinflated tire.

All four tires were substantially underinflated on 8% of the trucks and 3% of the cars.

NHTSA estimates that proper tire inflation could save 50 to 80 lives a year and prevent between 7,000 and 11,000 serious injuries.

Congress responded to the Firestone case by passing legislation that will require new vehicles to have a tire-pressure warning device as standard equipment by 2004.

http://www.classactiondefense.com/CM...ications25.asp

The tire litigation arises out of three basic allegations: (1) a design defect in the Ford Explorer which caused it to roll over with unusual frequency; (2) a design defect in certain Bridgestone/Firestone tires which caused the tire treads to separate prematurely; and (3) a conspiracy by the two companies to conceal the design defect of the Ford Explorer by intentionally underinflating the original issue Firestone tires. The underinflation had the intended effect of reducing the rollover caused by the design defect, but the unintended effect of exacerbating the tread separation defects, thereby creating different and more serious safety issues. These problems have allegedly caused more than 150 deaths, and have resulted in more than 240 lawsuits filed in the federal courts around the country, plus hundreds more filed in state courts.

http://dailybeacon.utk.edu/article.php/7046

Chances are you've driven around with one or more of your vehicle's tires underinflated at one time or another.

You're not alone. A federal government study last year estimated more than one in four cars, and one in three sport utility vehicles, vans and pickup trucks have at least one significantly underinflated tire.

Underinflation contributes to tire wear and tear, greater stopping distances and lower fuel economy.

Worse, it can lead to crashes, since over time underinflated tires - with sidewalls flexing and heat building up - can be damaged and even fail.

Remember what tire failures such as tread separations and blowouts did in the Ford Explorer/Bridgestone-Firestone tire crisis of 2000. Deaths totaled more than 270 and injuries were over 700.

Originally posted by Mr. Pockets
I searched for a little bit and found no substantial evidence that Ford's recommended tire inflation pressure had anything to do with the tread separation that caused so many accidents.

As a matter of fact, the bulk of Firestone's claims concerning the Explorer's safety focused on the car's handling after the tread separated. Firestone claimed, in a number of complaints to the NHTSA, that the Explorer was more likely to lose control and roll over after tread separation than other similar SUV models. The NHTSA's opinion was that the data available simply didn't support those claims.

I found no mention anywhere that anybody claimed that Ford's lower recommended tire pressure caused either the tread separation or the rollovers.

So, Porter, despite the fact that you have ignored my request twice now, I ask you again: what evidence do you have to support your claim that Ford's recommended tire pressure caused either the tread separation or the rollovers?

Did you somehow miss my above posts? Scroll back up a bit.

Running lower than 30-35psi in the tires causes excessive heat and stress on the tire, according to Firestone.

Running higher than 26psi in the tires causes the Explorer to tend to roll-over, according to Ford.

Am I not making sense?

[Mr. Pockets]

Originally posted by Porter



Did you somehow miss my above posts? Scroll back up a bit.

No, you posted the links while I was typing that. Sorry.

Originally posted by Mr. Pockets


No, you posted the links while I was typing that. Sorry.

oops, sorry. jumped the gun...

[benebob]

Originally posted by Porter

If you are running anything less than a sport oriented all-season tire on the SVX, you might want to consider getting a real set of tires. I have found the winter traction on the Potenza RE950 to be quite acceptable, even driving in the mountains in heavy snow and icy conditions.


You may want to take notice that BMW and Mercedes do not recommend 28psi... they recommend 35-40 depending on the tires, and I've never heard anyone call the ride "harsh" in a Mercedes.

Potenza RE950s SUCK for braking in ice and packed snow. They have decent traction in soft snow but that is all. Then you pay for it with noise when its not snowing. My brat has better snow stopping distances with $19 Crap tires in the stuff then my SVX with the RE950s when I had them on. I found that my Yoko A540s balance out decently for winter and somewhat acceptable summer driving but they haven't been made for 2 years now.

I find it interesting that you feel the need to compare it to other European vehicles. How about a 308? The factory recommended pressure is 29 for that? I have a Ferarri tech sitting right beside me. He also tends to disagree with your and I quote him "ricer go fast ideas" but then again that might be b/c he doesn't want to spend $5000 a year replacing parts on his 308's suspension just so that he can pull an extra .02g on the track.

Originally posted by benebob


Potenza RE950s SUCK for braking in ice and packed snow. They have decent traction in soft snow but that is all. Then you pay for it with noise when its not snowing. My brat has better snow stopping distances with $19 Crap tires in the stuff then my SVX with the RE950s when I had them on. I found that my Yoko A540s balance out decently for winter and somewhat acceptable summer driving but they haven't been made for 2 years now.

I find it interesting that you feel the need to compare it to other European vehicles. How about a 308? The factory recommended pressure is 29 for that? I have a Ferarri tech sitting right beside me. He also tends to disagree with your and I quote him "ricer go fast ideas" but then again that might be b/c he doesn't want to spend $5000 a year replacing parts on his 308's suspension just so that he can pull an extra .02g on the track.

Your statements and your attitude are both offensive. "Ricer go fast"? Give me a break. You obviously have me confused with my inferiors. I've never street raced in my life, nor would I associate with those who do. That entire culture is irritating and annoying in the extreme. My background is primarily in wrenching and tuning turbo Saabs and Subarus... sorry if that's not "elite" enough for your illustrious friend.

To respond to the point at hand, I have RE950s on my SVX right now, they are incredibly quiet at all speeds and performed admirably on packed snow and ice when I was driving in the VA mountains over the winter. They're certainly no Hakkapilettas but they're tolerable in winter weather.

I have 14,000 hard driven miles on them and they have surprised me by keeping their grip and their tread.. they are wearing slowly. I run 46f/42r on the street and the wear is even and displays no evidence of tread damage or excessive center wear.