Wore my tires out.

[svx_commuter]

I got Yoko AVS db's about a year and now I wore them out. The tread on the inside is cupped all the way around the tire. I get a nice whineing noise on the highway and a rumble when i slow down. I had the alignment checked and it was out a half of a degree which doesn't seem that bad to me. I think something else is wrong but I am not sure what. Everything else checked out okay. I was running the tire pressure low by about 3 pounds and didn't rotate the tire that often. Is that what did this? Before I get new tires I want to know this is fixed so they don't do it too.

[gl1674]

Change the driver - get one that does not brake in turns.

Apparently cupped tires are a sign that you were decelerating in turns or so I was told. The correct (and faster) technique is to brake in the straight line and accelerate through the turn.

Wear on the inside may also be a sign of wrong camber.
Apparently the factory service manual lists a different number
compared to what is in the electronic database in places like Big-O tires. Not a big deal, half a degree difference, but still.
I don't remember exactly, something like Big O says 0.5 degree, but factory manual says 0.1 degree...

i bought a set of dB's last summer and they wore out by this winter.. these tires have a pretty low treadlife expectancy, which i made the mistake of overlooking when i was tire shopping last year..

i wore my dB's so thin that one day, the inner sidewall of my front-right tire ripped wide open and left me pretty stranded..

-adam

[Seraph]

Originally posted by gl1674
The correct (and faster) technique is to brake in the straight line and accelerate through the turn.

Seen the F1 Races? Same thing. I do that as well (oh and drifting). Either other people are not quick enough or they think I am drunk but at turns, I normally loose a lot of people.

[svx_commuter]

I hope I didn't mislead anyone, it was supposed be tire "chop" and not "cupping". Going around the outside of the tire, the surface looks like ocean waves getting ready to break.

Yes I did some fast braking and turning when I got the tires. It was fun but expensive.

Adam, The db tire tread has three sections inside, middle and outside, the middle and outside look great. The inside has the chop and is worn almost to the wear bars. This is what you saw on your tires.

Your tire pressures were too low.


You should run the fronts at max pressure listed on the tire, the rears at 3-4psi lower than that.

If you were going by the doorjamb pressures, you were probably about 10psi low.



Your tread "cupping" is the result of extreme sidewall deflection under lateral loads (cornering) and is destructive to the tire. Basically, the tire doesn't have enough air pressure in it to retain its shape under load.

Pump those babies up!


Many people say, "Oh gosh my ride is so harsh now that I have higher air pressures in the tires..." ....that's because your struts are probably worn out and need to be replaced. Based on my experience with Subarus I'd expect a set of stock SVX struts to last 60,000 miles under average driving. After that the valving starts to lock up and you get a "bang" effect when driving over bumps.

[svx_commuter]

New struts again. I am getting real good at putting struts. This will be the 3rd set in 80k miles. That's what happens from driving the rough road. I also think I will change back to the standard front strut mount and trash the stiffer one. Thanks

Your take on what happened is correct. I think the db's have a stiffer side wall.

[Mr. Pockets]

The wear spots you describe could be caused by a few things, but I suspect struts. A worn out strut doesn't hold the wheel to the road well and causes the bald spots you're seeing. If you're experiencing any other symptoms, like vibrations, it may be another worn out suspension part.

You should inflate the tires to the pressure recommended on the door frame. The reason you do this is to maintain the wheel's outside diameter that the transaxle was designed to cope with. This isn't necessarily important on a 2WD car, but on an AWD car it's essential.

Now, if you have aftermarket wheels that are larger than 16", I don't know how you make sure you're maintaining the right outside diameter.

I am on my second set of tires on my SVX. I rotate them regularly, keep them inflated to the recommended pressure for the car and they wear evenly. I have never heard anybody else suggest that I should inflate my tires to 10psi over the recommended pressure.

The recommended pressure on the doorjamb has nothing to do with what you should actually run in the aftermarket tires you have on the vehicle. You should always go by the indications on the tire.

The Ford Explorer recommended 20-24psi in the tires on the Explorer, and we all see what happened there. Doorjamb recommendations are essentially for the stock tires for only grandmothers to drive on. What I mean by that is that those pressures promote a very soft, pneumatic ride that the Japanese think we Americans prefer. I'll lay money on the table that the Japanese SVX doesn't list the same pressures on the doorjamb.

I know I'd break the bead on the tires if I drove around all the time with 30psi in them, I'd rip them free from the rim.

Tire pressure can be as big an upgrade to the handling of a car as a whole new suspension.

Originally posted by svx_commuter
New struts again. I am getting real good at putting struts. This will be the 3rd set in 80k miles. That's what happens from driving the rough road. I also think I will change back to the standard front strut mount and trash the stiffer one. Thanks

Your take on what happened is correct. I think the db's have a stiffer side wall.

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.

[Mr. Pockets]

Originally posted by Porter
The recommended pressure on the doorjamb has nothing to do with what you should actually run in the aftermarket tires you have on the vehicle. You should always go by the indications on the tire.

The Ford Explorer recommended 20-24psi in the tires on the Explorer, and we all see what happened there. Doorjamb recommendations are essentially for the stock tires for only grandmothers to drive on. What I mean by that is that those pressures promote a very soft, pneumatic ride that the Japanese think we Americans prefer. I'll lay money on the table that the Japanese SVX doesn't list the same pressures on the doorjamb.

I know I'd break the bead on the tires if I drove around all the time with 30psi in them, I'd rip them free from the rim.

Tire pressure can be as big an upgrade to the handling of a car as a whole new suspension.

First, your claim concerning the Explorer. I was under the impression that the tires themselves were defective. While I don't doubt that under-inflating the tires could have been a contributing factor, I never heard anything that suggested that Ford's recommended tire pressure was at fault. Do you have any documentation to support this claim? I'll look for myself, too.

I'd be interested to see what tire pressure is stamped on the Japanese SVXs.

I've never heard of tires with stiffer sidewalls causing the wear symptoms that svx_commuter described, but then I don't pretend to know anything about 'high-performance' tires. I only drive my SVX in the summer and I still have mud & snow rated tires on it.

[benebob]

Originally posted by Porter
Your tire pressures were too low.


You should run the fronts at max pressure listed on the tire, the rears at 3-4psi lower than that.

If you were going by the doorjamb pressures, you were probably about 10psi low.

I wouldn't suggest even coming with in 5psi of the max pressure for the tire. Maximum is exactly what it says maximum. If you put in the max pressure on a cool day with the tires cold (when you are told to check pressure) and then go out and drive like a F1 driver or even to work over the highway for a good spell when the outside temp heats up you will actually be running anywhere from 5-8psi higher than the max pressure. Not the brightest idea for daily driving esp on our lovely northeastern roads. What you'll end up with if you don't pop a tire before the treads get down is a tire that has no tread in the middle.

What happens with an underinflated sport tire is a little different from what happens with an underinflated touring tire.

The sport tire has stiffer, reinforced sidewalls that don't bend as much... so when the pressures are too low it tends to overstress those sidewalls and put more of the vehicle's weight on them, rather than riding on the air pressure.

During cornering, the whole tire deflects more than it should, and the sidewall bends, pulling the tread up slightly on the inside and causing the "cupping" or feathering effect. It's very damaging to tires and causes extreme premature wear.

Running higher pressures causes the tires to wear evenly all the way across and contributes to both longer tire life and better handling characteristics.

Originally posted by benebob


I wouldn't suggest even coming with in 5psi of the max pressure for the tire. Maximum is exactly what it says maximum. If you put in the max pressure on a cool day with the tires cold (when you are told to check pressure) and then go out and drive like a F1 driver or even to work over the highway for a good spell when the outside temp heats up you will actually be running anywhere from 5-8psi higher than the max pressure. Not the brightest idea for daily driving esp on our lovely northeastern roads. What you'll end up with if you don't pop a tire before the treads get down is a tire that has no tread in the middle.

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 55psi.

"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.

[Mr. Pockets]

Originally posted by Porter
What happens with an underinflated sport tire is a little different from what happens with an underinflated touring tire.

The sport tire has stiffer, reinforced sidewalls that don't bend as much... so when the pressures are too low it tends to overstress those sidewalls and put more of the vehicle's weight on them, rather than riding on the air pressure.

During cornering, the whole tire deflects more than it should, and the sidewall bends, pulling the tread up slightly on the inside and causing the "cupping" or feathering effect. It's very damaging to tires and causes extreme premature wear.

Running higher pressures causes the tires to wear evenly all the way across and contributes to both longer tire life and better handling characteristics.

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.