filmteknik

2008 RX350, around 140K miles

I am on Bridgestone Dueler Alenzas and they are the only tires I've had after the OEM Michelins. They are at the end of life. Wear has been extremely even and I've only done rotations a few times as I would look at see only insignificant differences between fronts and rears. Oftentimes the fronts seeming to have a hair less wear than the rear and as I presume front is the more critical position, I've left them be.

Yesterday, however, I noticed severe wear on the left front tire at the extreme sides. I had been noticing some speed related oscillation and thought maybe it had lost a balance weight so went to check it out. The wear at the sides is so much so that it's not safe to continue on it, even for the brief time while I shop for new tires. It's almost like it was running on low inflation for a long time. But that hasn't been the case. If anything, I run a couple pounds over spec. (Severe over inflation would cause excessive center wear, under would cause side wear.)

So question number 1: What would cause this?

When I got the Bridgestones they gave me numbers saying they took measurements and how I needed an alignment yada yada. I said I would think about it but given how even the wear had been on the OEM Michelins I never did go back. I am now at over 80K on the Bridgestones and until this current issue the wear has been very even, among tires and across each tire as well. So no regrets there. One reason to want to continue for a few more miles on these is because I want to see if the tire now in the LF position starts wearing abnormally then I will know for sure that I need some alignment work done and I can make a more informed decision about including an alignment when the next vendor tries to upsell me. Don't doubt it might be a good idea but it sure wasn't needed last time.

I have placed my spare which is the original Michelin into service. It has only ever seen use as a spare for a few miles* so presumably it's going to be slightly larger in diameter than the other 3.

So question number 2: Is that an issue? I put it in the Left Rear position. As I said I am now researching new tires but good to know how much of a hurry I need to be in. The "bad" tire is now the spare. Good enough to limp home in an emergency I believe.

* I never included the spare in the rotation because unless the recommendations for radial ply tires has changed, per Lexus at the time, one was not supposed to interchange between sides. Seems like one side having the work divided among three tires instead of two would result in only 67% of the mileage which would be a major difference in wear.

lex_rx

If I remember the manual for the 2nd gen, a full size spare should be part of the rotation. That's how I did it mine. Check your manual.

filmteknik

Yes, I know that. On the right side only per the diagram. I chose not to include it in the rotation because the wear would be uneven because the "work" of the right side would be spread among 3 tires while the left would be among 2. So over the long haul the 3 tires would rack up only 67% of the mileage as those on the other side. Is that still the case, that radial ply tires should not change sides (emergency use of spare excepted of course). Maybe the recommendation has changed over time. If the tire experts now say go ahead and cross over that changes things completely as the "work" of 4 positions is spread over 5 tires so for every, say, 100,000 miles you drive you are only putting 80,000 miles on each tire.

When I bought new tires one option would have been to buy 3 of the OEM type and put the spare into service, keeping one worn tire as the spare. But it's usually a better deal to buy 4. And I ended up buying Bridgestones for their much deeper tread and expected longer life. One thing I neglected to research was the effect on MPG. I think it may have dropped 1 or 2 which is not much but over the life of the tires might eat up most or all of the benefit of the longer life. Oh well.

DennisMik

Your tire wear problem is the car, not the tire. Most likely the camber setting. You probably hit something hard enough to knock the alignment out of spec. So get the front end aligned before you start seeing wear on the spare.

Using a fresh tire with no wear in place of a worn out tire will not be a problem. The only concern would be if you had a limited slip differential and you were using 2 tires that were radically different sizes. The difference in diameter between a new and a worn tire is too small to be of concern even if you do have limited slip..

filmteknik

Thanks; I will look into it. But wouldn't out of wack camber cause excessive wear just to one side? I have it on both.

Here is the bad tire; now relegated to carefully-limp-home spare. I dropped it to double check the pressure which was fine.

DennisMik

One edge of the tire being worn in a narrow band is severe camber misalignment. Your photo looks like a mild misalignment driven for many miles. The other edge could be normal wear from cornering.

Here is a photo of severe camber misalignment wear:


Here is a photo of mild camber misalignment wear:

filmteknik

Ah, thanks. So not a panic but I should spring for an alignment with new tires. And keep a close eye on the LF replacement for these remaining few miles.