A few months ago, I bought new tires (Michelin Zero Pressure) and had the car aligned. It had worn the front right tire to the cord on the inside, and the front left on the outside, and the left rear on the inside. Obviously, something was off.

Since the new tires and alignment, my car seems less "solid" ... sorta floats above 80, plus the wind seems to bother it more now (before, there seemed to be no effect at all from a stiff crosswind or getting behind a truck).

I'm thinking the alignment is set a little wrong, maybe for minimum tire wear and not for drivability. Obviously, I don't want to wear my $1400 tires out in a hurry, but I would like for it to drive like a Vette instead of a Buick. Of course, the Michelins could not be as good as the Goodyears, but I doubt that.

What specs should I give the alignment guy when I take it in tomorrow? I've seen several sets of specs on the forum recently, but they all seem different.

 

Rocketdawg,

Can't help you on the specs (haven't done yet on our 2000), however, on our 1994, went with the GM manual specs and the car rode well.

Generally positive toe-in or negative camber can cause what you describe.

Also, the alignment equipment calibration and set-up (on the car) is very important, otherwise the 'print outs' of the settings (before/after) aren't worth the paper their printed on. So, consider asking for a different tech to do it this time (if possible) and be sure to compare the previous 'after' to this time's 'before' to look for evidence of equipment problems or the Tech's lack of training.

Lastly, what tire pressure did you set the new tires at and was it with a reliable gauge, as high tire pressure could also account for the 'float' feeling.

 

Admiral, I didn't get a printout when he did the alignment ... I never thought about it at the time, and apparently they didn't either.

As soon as I got home with the new tires and they'd cooled, I checked the pressure. None of them were the same, and all were high, so I released air 'til they were all down to 30. Since then, I've tweaked them a couple of times with my compressor (for the onset of cold weather, and a couple times more), so they stay at 30 cold. I use a digital gauge and the DIC readings verify those of my gauge to within 1 psi. So I don't think pressure is the problem.

NTB did the alignment, and they had some sort of new laser machine that they were high on. I'm not sure if it's the best available or not.

 

Rocketdawg,

Sounds like you didn't get a good tech doing your alignment.

Any good alignment tech will check the tire pressure to assure it is at least the same per axle and preferrably set to manufacturer specs all the way around (especially since it sounds like you got your new tires put on and the alignment done all at the same time -- so it should have been set to 'cold' readings all the way around).

Further, they should bounce the car a few times after lifting to attach the alignment equipment to each wheel, to assure it has settled into its 'neutral' position and I believe even taken the car for a quick trip around the block after the new tires were installed to assure everything had settled into place.

As the tire pressure was uneven, it could have thrown-off both the camber and caster, which can then affect toe.

Hopefully the manager will recognize this and grant you a re-alignment without any question. But if not, raise a stink, especially after dropping over $1K on tires.

Regarding the 'laser machine', any machine if properly calibrated and set-up should work fine.

And unfortunately, no matter how technologically advanced the equipment, "a fool with a tool, is still a fool".

BTW, regarding tire pressure. Consider changing the tire pressure up/down by 2-3 PSI cold and see what that does, I know increasing to 33 PSI made an amazing (and I really mean amazing) improvement on our 1994 with OEM Goodyear GSC's.

And I know there's a lot of discussion on tire pressure here on the Forum about keeping it at 30 PSI hot, but take note that many suggesting this are also running larger than stock size tires, and since your running the Michelin's, they might require slightly more or less tire pressure to maintain their 'flat-foot'.

 

 

Sounds like a different feel with the new tires. ANYTHING will feel different than the original tires. Remember, what feels more loose may not be. The original tires had very stiff sidewalls, so the new ones will feel loose even though they may actually be gripping better.