When the OEM S02s wore out on my '01 AP1, the inside treads of the fronts were worn off, and the back treads were getting pretty bald evenly . The car had a little over 10K on the ODO. So, I had my allignment changed to straignten up the settings, and went with non- OEM tires, using 205/55/16s on front and changing to 245/45/16s on the rear -- as per instructions learned from this forum.

Now, 16K later, I find that the fronts still look pretty new, but the rears are worn bald in the middle. The sides of the rear treads are near perfect, but the middles are shot! I've got some new rears on the way. I have never run more than 32 psi in any of these tires.

I have been advised that the problem is that my stock rear wheels aren't really wide enough for the 245/45/16s, causing them to "bow out" in the middle, and thus causing the wear there.

Is this true? And if it is, would running lower pressure in the rears help this problem? Or do I need to "tweak" the rear allignment a bit more? I know I could change all four wheels, but really don't want to do that at this late date in my ownership of this car. And, I have zero desire to go to 17 or 18 wheels, as I feel theis car rides harsh enough already.

Thanks,
Richard

 

Richard, I don't really have any good ideas for you. 16K is really pretty good for a lot of models of tires, I've never gotten more than 10K out of Bridgestone S02's or RE050's rears. Maybe your 245's run extra wide? I just went up a size on the OEM 17's, but prior to that I have only been running tires whose section width matched the rims they were on.
Center wear is a traditional indicator of high pressure, it pretty much rules out excessive toe or camber. You could try going down to 30 psi, but I wouldn't run any lower.
Good luck!
Mike

 

Actually, my tires with which I replaced my OEM SO2s were Falken FK 451s. The tread width was pretty much the same as the OEM 225/50/16. Maybe the 16K rear tire wear is as good as I can do, I don't know. And the odd thing is that the rear tire on the driver's side is the real problem. I could probably get another 5K out of the passenger side rear, if I could.

Would it do any good, when I get my new rears installed, to have a four wheel allignment with me sitting in the driver's seat? I've heard of this before, as these complex suspensions allign differently when weight is applied. (perhaps I should just go on a diet!) No, actually, I weight about 170, which should not be that unusual.

And the thing that just freaks me out is that the front tires look like they could go for another 20K!

This is really wierd. Since I'm driving an S 2000, it pretty well rules out any "rubber burning" from standing start. Were that the case, I would also be complaining about a blown clutch!

Thanks,
Richard

 

There's currently a thread in S2000 talk about tire wear. The general consensus seems to be something close to 2 to 1 for consumption of rears to fronts. Every bit of force, both accelerating and braking (downshifting) that is exerted by the engine is delivered through the rear wheels. (I hardly use my brakes for 'normal' street driving)
I'm not sure if there is a R-L bias in the torsen diff., I'm sure someone more knowledgable than me can chime in on that. The 170 lb difference is somewhere around 7% of the total weight of the car, maybe the difference in wear is = to the difference in weight.
I personally am currently running the AP2 stock alignment specs and I'm getting around 10K (to the wearbars) from the rears, and 20K from the fronts. When I was running UK and various high toe, high camber autocrossing alignments, I was getting 6K/10K F/R at the most.
I doubt futzing around with your alignment will give you much if any change to your wear.
Sounds like what you are experiencing is pretty normal, except for the center tread wear, and I'm guessing that is a rim width issue, or just something to do with the way those particular tires are made.
Cheers,
Mike

 

Well, I wonder just for the sake of being really crazy, what would happen if I had 0 toe in on the rears?

Thanks,
Richard

 

You should do aligment with two new rears with you sitting in driver seat. Also, flip the rear tires inside out when they are down to about 1/2 tread life then swap left to right to even out the wear.

 

I would have swapped the rears side to side, but they both wore our envenly in the midle!

Thanks,
Richard

 

If I understand the geometery correctly, zero toe in the rears will significantly reduce grip, all other factors being equal.

 

What is the tire pressure?

 

I kept the tire pressure at 32 psi rather religiously. Once, however, I forgot to check the tires when the weather changed form hot to cold rather abruptly, had the car serviced, and found I was running on only 22 psi! Any damage that might have done, however, would seem to have been to the tread edges, not the middle.

Thanks,
Richard