Tires: 6 bad Michelin Tires?, michelin pilot sport, michelin tires

Question
QUESTION: Hi Barry,
Thanks for answering my question on tire repairs a week or so ago.
I just put Michelin Pilot Sport A/S Plus 245/40ZR-18 93Y on my 06 GS430.
Car aligned by dealer
Spec here : http://i62.photobucket.com/albums/h104/GreenTennis/Tires/IMGP5658.jpg

Since getting these tires, they have been drifting to the right.  DT rotated front to back (they did not want to cross over the fronts to see if the drift went in opposite direction).
Still drift to right.  DT replaces both front tires.  Still drifts to right.

Went to the dealer:

The lead tech, diagnostic tech and I went for a test drive. Good news is that they said: it is drifting. Good news stops there.

They do what DT did not want to do. They swapped the front tires for testing. Now the car drifts slightly to the left or either drives straight. Not as bad as it does to right when the tires are in the right direction.  Dealer states..  Tire conicity.

That means I have received 6 bad tires?? Dealer says they deal with this quite often but is rare for Michelins. Since they are directional, options are not there. I will be calling Michelin! This is just not right. Is this common?  Are the tolerances for these tires not tight enough for this car?  Bad batch of tires?  The car drove straight as an arrow before.
Your thoughts?   DOT Code: 4M 88 002X

Thanks


ANSWER: Mike,

Usually when you swap tires left to right, Either 1) the direction changes (in which case, it is the tires, 2) There isn't any change in direction (which means it's alignment), or the drift disappears and that means it is both)

The fact that you have a change in direction - but not as bad as before sounds like it is mostly the the tire, but there's a bit the alignment there, too.

It does seem extremely unusual to have 6 bad tires.

But diagnosing this from a distance is difficult.  So let's start with the basics.

1)  What is the tire size and pressure?

2)  Is that the original size and pressure for the vehicle?

On every vehicle sold in the US, there is a sticker – commonly called the tire placard - that lists the original tire size and the proper pressure for that size.  The placard is usually located on a doorpost or in the glove box – but sometimes it is located in the trunk or on the fuel filler door.

Let's start there and post a followup.

Thanks





---------- FOLLOW-UP ----------

QUESTION: Hi Barry,

“What is the tire size and pressure?”
The rims are stock and tire size is 245/40ZR-18.  Same size as the OEM tires.
The sticker you mention is 33psi cold.  They were set at 33psi when the tires were place on the car a few days ago.  I just check hot after 30+ miles and they are running 37 all the way around.

“Is that the original size and pressure for the vehicle?”
Yes


Thanks
Just to note, Camber and Caster can not be adjusted on this car.


Answer
Mike,

Thanks for the reply.

OK, so the tires are the original size and the pressure is set to thespecification.

Did you verify that yourself, or are you assuming that someone else did it correctly?

Next step:  Are there special conditions when you notice the drift?  Put another way, is the drift always there or do you only notice it under certain conditions?