Treadwear - when to say when?

[rquintero]

I've put 5k miles on my rear OEM Yokos and the two inside threads are completely gone, and I mean completely. The outer threads look reasonably good. No surprises here.

I was going to attend one last track event (tomorrow) with them, given that there was no rain in the forecast.

But then I wimped out - round trip to the Sebring track would be about 340 miles, and I wasn't sure if the tires would take even that. Then at least 80 miles of track, who knows how much more wear that is.

Out of curiosity at this point: how much tire is left after the tread is no longer visible? Again, asking for dry track use, not street driving.

 

[hgunnerz]

Not Much. I went from Dallas to Orlando. When I left Dallas I had some tread (not much, about a 1/4"). When I stopped in Baton Rouge,LA I had almost no tread on the inside. I thought I could nurse it to Florida. Not even close, about 100 Mi more and all I had left were the cords coming out of the tires (no rubber left, only cords) and stuck with TWO bad tires at a rest stop on I-10! Major mistake I will not make again. Too expensive of a car to risk it.

 

[weiku]

When you're smooth on the inside 1/3 of the OEM tire, you're probably around 350-400 miles away from the cords, and when you hit the cords, you're asking for trouble.

You said that the outside of the tire is looking "ok"...perhaps try to take out some of the negative camber (1/2 degree or so) if you want more even tire wear.

Andie

 

[hejo]

Originally posted by weiku:
You said that the outside of the tire is looking "ok"...perhaps try to take out some of the negative camber (1/2 degree or so) if you want more even tire wear.
Andie

Also make sure and key a close eye on tire pressure. I'm sure the FAW Nazi will point us to the right link

------------------
Hal Jones
Lake Oswego, Oregon
95T Blk\Blk SportShift

 

[johndoh]

Originally posted by rquintero:
The outer threads look reasonably good. No surprises here.

Very odd. I thought that the rears have Toe-Out which will wear out the outside part of the tires more and fronts have Toe-In which will wear out the inside part of the tires first. My rears are currently wearing down more on the outside of tires to confirm this.

 

[rquintero]

Thanks guys, at least I feel a bit less stupid now for NOT going to the Sebring event.

Re: Toe - this is a Y2K, completely stock, and I keep the tires at the recommended PSI.

Given that the rears are wearing so evenly I doubt there is a problem and think that the Yokos were intended to wear that way.

[This message has been edited by rquintero (edited 06 May 2001).]

 

[ChopsJazz]

Also, considering the reasons for the extreme tirewear on the NSX (alignment settings that are dialed in for crisper cornering), driving in a straight line is the worst thing you can do to these tires. Conversely, a trip to the track helps to even out the wear pattern as hard cornering loads the outside of each tire.

 

[rquintero]

>> hard cornering loads the outside of each tire

I didn't know that.

I can see that happening to the outside of the tires on the side that is on the outside of the turn (that sounded weird!) but never gave much thought to what happens to the inside tire...

I would have thought that the tires on the inside of a turn would have the load toward the inside of a tire.

In other words, in a track with predominantly righ hand turns, I would be evening out my driver side tires but making the passenger ones even worse. Not so?

Thanks,

Ralph

 

[weiku]

Originally posted by johndoh:
Very odd. I thought that the rears have Toe-Out which will wear out the outside part of the tires more and fronts have Toe-In which will wear out the inside part of the tires first. My rears are currently wearing down more on the outside of tires to confirm this.

The NSX has negative camber, toe out, and positive caster in the FRONT, and negative camber, toe in in the REAR (no caster adjustment in the rear). OEM tires are also corner specific with a pre-wound internal bias for each corner. That aside, with any kind of tire, the NSX will tend to wear tires faster on the inside 1/3 or so, because of the negative camber front and rear, and the toe out in the front and toe in in the rear.

Andie

 

[weiku]

The other note I should add is that when I have the NSX aligned WITHOUT my butt in the cockpit, I see more tire wear on the inside of the left front and left rear tires as compared to the right side. I believe this is because when I sit in the car, it induces a bit more (0.2 to 0.4 degrees, say?) negative camber on the left side, which causes the faster tire wear on those sides.
I only weigh 150lb...not a big guy by any means, but this seems to be enough to cause this tire wear phenomenon.

Now, the other possibility is that I mainly drive in the left lane on the highway, and we have serious ruts here in Michigan, plus the crown of the road surface means you need to steer the car slightly to the right to keep it straight (i.e. the road surface is not perfectly flat...what road is?)...and this may be causing the faster wear on the inside of the left tires as well.

Andie

 

[sjs]

Originally posted by johndoh:
Very odd. I thought that the rears have Toe-Out which will wear out the outside part of the tires more and fronts have Toe-In which will wear out the inside part of the tires first. My rears are currently wearing down more on the outside of tires to confirm this.

The toe setttings are a minor factor (in terms of wear inside vs outside) compared to the negative camber.

Here's an idea. Since they're corner specific anyway, why not design them with a slightly shorter sidewall inside to make the tread flat on the ground at stock camber settings? Surely a silly idea or someone would have done it.

 

[weiku]

Originally posted by sjs:
The toe setttings are a minor factor (in terms of wear inside vs outside) compared to the negative camber.

Here's an idea. Since they're corner specific anyway, why not design them with a slightly shorter sidewall inside to make the tread flat on the ground at stock camber settings? Surely a silly idea or someone would have done it.

I would think they would still wear unevenly, even if they started out perfectly flat across the tread because of a shorter sidewall on the inside. I think we'd be looking at $500 tires each for the engineering that would have to go into that.

 

[nsxtasy]

Most street tires are manufactured with 10/32" of tread. When they reach 2/32" of tread, the "tread bars" or "wear bars" appear. These are half-inch strips across the tread where the depth of the tread is 2/32" less than elsewhere. This is about when you ought to replace the tires.

Not sure if it came through in the comments above, but if you have worn the tread out so that it's flat (no tread) - even if it's only for part of the tread width - you should replace the tires.

My OEM tires wear pretty evenly across the tread. But that includes some track usage.

 

[nsx4jlp]

Is there any way to correct the camber closer to zero?

 

[nsx4jlp]

Is there any way to correct the camber closer to zero?

 

[ChopsJazz]

The toe settings point the tire in one direction or another. The front tires of the NSX are toed-out.
Camber is what tilts the tires from side to side. In the case of the NSX the top tilts in (negative).
The toe-out insures quick turn-in because the inside tire is already pointed a little bit in that direction. (The toe-out scrubs the tire a little but not in the way that the negative camber does.)
The negative camber acts in a way to give the tire needing the most traction, the outside, the biggest contact patch. When the car takes a set in a corner, the outside tire is loaded, leveling out the tire contact patch (much in the same way F1 cars do). The car rolls over on the outside tire taking the load off the inside front tire. Have you ever noticed the inside front tire of a car at speed coming down th eCork Screw? Sometimes that tire barely touches the ground!
The rear tires have toe-in to counter the overall effect of the fronts and help the car track in a straight line.

[This message has been edited by ChopsJazz (edited 13 May 2001).]