Inner edge of the tire worn significantly more

[PandaBear]

than the rest of the tires.

Factory OEM 225/40/18, manufactured 44th week of 07 with 31k miles life, on IS250 RWD Front axles. This seems to be a common problem on this car due to the factory "toe out" alignment spec. I am wondering other than going to a racing alignment shop that will do a more precise / neutral toe alignment, and get new tires. What else should I do to prevent this from happening again?

Was thinking about "flipping" the tires inside out, but I'd imagine most reputable tire shops won't take the chance of blow out and get sued, and the gain in life is negligible.

I am not sure if a franchise will go "out of factory spec" for me to make the tire life longer.

 

[HTSS_TR]

I think if you could find an independent alignment shop they would do the zero toe and minimum camber to reduce the inner wear. Also, inflate the tires by about 5-6 PSI will reduce the outside wear too. Flipping the tires before mid-life will even out the inner wear, I done that for my S2000.

 

[PandaBear]

A friend that goes to track on a regular basis gave me a call. He said based on the tire observation it is most likely toe out and negative camber. The toe out is the one that causes the majority of the inner 1/2" edge wear.

One thing I forgot to mention, is that when I steer the car, most of the steering wheel range the car would want to center itself, until I reaches the last 1/8 of a turn near the lock at the extreme left / right, then the car would want to steer toward where I try to. For example, when I try to do a U turn by steering the car toward the left, when I am almost having the steering wheel turned to the left end lock, the car would suddenly want to pull to the left rather than pulling back to centering itself. Friend told me this is a symptom of a toe out issue.

The recommendation is to buy new tires within 1k miles, and do a "custom" alignment with the new tires to have minimal toe and camber in a tuner shop.

 

[spasm3]

6/32 in the middle, 1/32 on on side 3/32 on the other, i would run a bit more air pressure, but thats just me.

 

[Hokiefyd]

The tread on the shoulders is often not as deep as the tread in the middle. It looks to me that the "floor" of the tread grooves on the outer edge of the tire are stepped up compared with the floor of the main tread grooves.

In other words, I'm not sure your measurements necessarily indicate a problem. I think it's just the "topography" of the tire.

 

[CapriRacer]

PandaBear,

Well, I started to write one response, and then took a much closer look at the photos, did a bit of research, and I am now writing a different response.

First, I thought it was funny that you were commenting on the front tires - which made me think you either had a staggered fitment, or you didn't rotate tires enough. It was staggered tire sizing, so in some respects the tire wear you are getting is just what is expected with a RWD car - the shoulders on the front tires are wearing more, while the rear tires should be wearing more in the center.

While there is a bit of difference between the outside grooves and the inside grooves, the real difference is in the shoulders. Some would suggest this is due to under-inflation and recommend you add more inflation pressure - but there are some reasons to discount that.

Because many vehicle manufacturers require low values of rolling resistance for their tires, it is common for tire enginners to shape the outermost rib to curve more - and that results in less tread depth and less material.

But it is also possible that your vehicle has a high level of caster. Caster adds camber as the steering wheel is turned.

It is also possible that you have high levels of Ackerman - increasing toe out as the steering wheel is turned. Your second post indicated such.

But I suspect the real problem is that you are doing a lot of sharp corners, which is putting a lot of cornering wear on the shoulders. You may want to consider driving less agressively - especially when doing sharp corners.

 

[Sayjac]

OT, but yet another example of why I always enjoy and appreciate CapriR's contributions to the tire board.

Even if I don't always completely understand them.

 

[bullwinkle]

CapriR is exactly right-even though they don't handle well-that is exactly what happens to my tires on the 4X4 Dodge Rams I've had when they don't get rotated often enough-the shoulders wear rapidly on the fronts-I've actually started running 75 PSI (load range E/10 ply tire) which seems to help somewhat.

 

[spasm3]

You know, that makes a lot of sense!!!

 

[HTSS_TR]

Originally Posted By: CapriRacer
PandaBear,

Well, I started to write one response, and then took a much closer look at the photos, did a bit of research, and I am now writing a different response.

First, I thought it was funny that you were commenting on the front tires - which made me think you either had a staggered fitment, or you didn't rotate tires enough. It was staggered tire sizing, so in some respects the tire wear you are getting is just what is expected with a RWD car - the shoulders on the front tires are wearing more, while the rear tires should be wearing more in the center.

While there is a bit of difference between the outside grooves and the inside grooves, the real difference is in the shoulders. Some would suggest this is due to under-inflation and recommend you add more inflation pressure - but there are some reasons to discount that.

Because many vehicle manufacturers require low values of rolling resistance for their tires, it is common for tire enginners to shape the outermost rib to curve more - and that results in less tread depth and less material.

But it is also possible that your vehicle has a high level of caster. Caster adds camber as the steering wheel is turned.

It is also possible that you have high levels of Ackerman - increasing toe out as the steering wheel is turned. Your second post indicated such.

But I suspect the real problem is that you are doing a lot of sharp corners, which is putting a lot of cornering wear on the shoulders. You may want to consider driving less aggressively - especially when doing sharp corners.

Driving less aggressively = less fun. Instead of having fun taking 50 MPH at recommended 30 MPH on ramp, he should drive only 25-30 MPH and having no fun doing so ?

I rather do an alignment with minimum toe out or zero toe or even some toe in, plus minimum negative camber and inflate front tires about 3-6 PSI above placard. If the inner tread still wear out faster than outer tread, I would flip the tires just before half-life. By doing these things you may increase the tire life by 15-20%.

 

[PandaBear]

CapriRacer,

You are right, what I meant was the inner shoulder have a significant "cut" that resemble a rub against hard object rather than a normal gradual tire wear due to tire inflation or camber. When I first notice this wear, I though there were objects clinging inside the fender well that was rubbing against the tire to scrape away the shoulder. However, once I found all the blow out photos of front tires of this car on the Internet (all have 4/32 and above trend depth all around except the inner shoulder), I conclude that this is the alignment design of the car rather than any scraping.

This car has a staggered setup, 225 40 18 front and 255 40 18 rear. I rotate the tire left/right about every 4-6k miles. Usually when I start hearing tire noise or when I feel a minor amount of wear difference between on the "landing" edge of the trend blocks and the "take off" edge of the trend blocks.

The factory spec pressure is usually 35 PSI. Because of my wife's back injury and her sensitivity to road imperfection, I usually let it go between 32-35 PSI. Actually the outer edge wear, despite being 3/32 rather than 4-5/32, seems fine with me as I do notice that it has fewer material on the edge even when the tire is new. Unlike other cars (all FWD) I've driven in the past, when steering this car to the extreme left / right end, the steering wheel tends to pull away from the center rather than self center.

The car is driven very conservatively for long commute (40 miles at a time) and local short trip, proven by the above EPA fuel economy (wife gets 31-32mpg vs EPA 29mpg). The only "sharp turn" is when the car is making a U turn.

 

[rpn453]

I'd probably just extend the tie-rods a bit to get rid of the toe-out condition and see what happens. What is the reason for having toe-out on the front of a RWD car?