tire wear

[RICH MUISE]

I'm running P215 70 15's on the front of my car. I have about 18.5k miles on them, and my outer edges on both tires are worn almost smooth. I'm wondering what you guys with wider tires like mine are getting for mileage from them, and if you have similar wear patterns.
I've had the alignment checked, and it's where it was as he set it 2 years ago. I haven't had balancing checked, but I have zero shake in the car up to 85mph, so I don't think I have a balance problem.
The tires are not 1/2 worn on the majority of the tire, just the outer edges. I know the tires are substantially wider than the car was designed for, so I'm wondering if it's the wider width that is the problem, and just something we have to live with if we want the width.

[terry_208]

I was under the impression that wear on the outer edges, outside, of tires meant that there was more pressure on that edge, either tow-in or camber.  I also understood too little tow-in and the car would wander, but I'm not an alignment man so I don't know.  I'll watch your post to learn.

[59meteor]

Normally if both outer shoulders are worn more than the center, the tire pressure is too low. Assuming you are running radial tires, I would think you would want to start around 32 PSI or so, depending on wheel width, and moniter for tire wear.

[hiball3985]

Too much positive camber or low pressure, I run mine at 35lb.

[gasman826]

Using a 1957 alignment spec, the modern tire is not going to like it.  The larger/wider the tire, the closer to 0º camber the more even wear across the tread.  Radials will perform better a little toward negative.  Radials have less rolling resistance than bias ply tires so toe-in should lean toward the minimum of the range (1/16-3/32 total).  Your wheels are wide enough and I assume you are not lead footing it around corners. 

[suede57ford]

My cars seem to rough up the inner edge pretty quick with 225-245 width tires.  My wife's SUV has 305's all the way around and it eats/cups the tires despite having it aligned multiple times.  My skinny front drag tires have some feathering on the inner edge as well in not many miles.   My super duty has aggressive mud tires and in 10,000 miles they are really rough to the feel, but i'm sure if I had stock Michellens they would go a long ways before getting a wear pattern.

I just accept that the cooler a tire looks the shorter the life is. 

[Lou]

If a tire cups, the balance is off.

[gasman826]

If a tire cups, the balance is off.

and/or shocks.

[gasman826]

Drag car needs a drag car alignment.  The front ride height changes dramatically through the quarter mile.  As the ride height changes so does the toe-in (as well as the caster and camber).  Having the toe off at 150 MPH really wears a tire.  Lay your hand flat on the tread and slide back and forth across the tread.  If the toe is off and wearing the tire, one edge of each tread will feel 'sharper' than the other edge.

Big, aggressive 4X4 tires need to be rotated regularly to keep them flat.  Many performance/specialty tires have a softer compound and they wear quicker.  Mud tires have big blocks of rubber on the out edge on the tread.  Looks great and are super for mud but don't hold up well to turning on hot pavement.

[SkylinerRon]

4X4's front alignment twist the outer edges up and then they wear off. Rotating tires front to rear every 5k miles cures this.

An up to date alignment and more air pressure should help a lot. Put them on the back if you can.

Ron.

[81TTA]

Rich, do you know what caster/camber specs were used on your car? 

Your question is very timely for me.  My Dad's '57 is showing the same kind of wear you describe on the front tires.  He's still running 14" tires.  I don't remember his overall mileage.  But, I'm sure it's somewhere between 2000 and 5000 miles since the alignment.  The wear is way too aggressive for so few miles.

I can't be too harsh about the guy who did the alignment since it was me!   But, since we replaced all the steering/suspension parts years ago, I'm having a tough time remembering what numbers I used originally to set caster/camber.  I don't have the service manual handy right now.  I *think* the specs are 1.00/1.00?  A few weeks ago when we noticed the tire wear, I moved the camber back a degree.  And, did a tire rotation front-to-back.  Handling didn't feel like it changed at all after the camber change.  We'll see if things improve after another few thousand miles.

I've heard the general trend for "performance driving" is camber = 0 (biased negative is better than positive) and as much caster as you can get while keeping camber in range.  If your car has any positive camber dialed in, it might be worth trying to move it back to see if it helps tire wear.

[RICH MUISE]

The alignment shop gave me a copy of the specs, I'll try to find it, but my car is modified somewhat in that I have R & P steering, dropped spindles, etc. As the fine print says, "your results (or needs)may be different". The guys here know much more about the alignment requirements than me.