So I finally got new Michelin premiers at Costcos. The process was smooth but now the car feels unsteady especially at higher speeds. it almost feels as it wants to wander off the lane, transiently, almost like with strong cross winds . the ride is fairly uncomfortable and tire noise is higher at speeds >70.

I am coming off Dunlop Grandtrek Touring AS, which i always felt they weren’t great tires, but now i think back and those feel like heaven compared to new Michelin Premiers.

Any thoughts? did Costco guys screw up something , or is it an alightment issue ? Also I have airmatic with active curve and ADS, not sure if it matters

What pressure are you running in those tires?

36- 37 psi each

36-37psi all4

I think Michelin has a 30 day warranty... take them back. It can often be too difficult to diagnose tire problems you're describing

New tires always need "break -in" period for the rubber to wear to vehicle pattern.
Than what model of Michelin did you get?
The brand is famous for long-lasting threads, what comes with hard rubber= poorer traction.
I loved Michelins for years, even I suffer with them on my ski trips, but then got good deal on Firehawks and they were way better in slippery conditions.
Lastly Michelin outpriced its value IMHO.

Have the balanced checked since I wouldn't expect alignment to have changed right at a tire change. I have the same Dunlop tires and they are junk. Look at tirerack.com and they have the lowest rating I've ever seen on tires, let alone on a MB.
I don't know about the other MB features, but the timing would be really coincidental if something malfunctioned right at a tire change.

How many miles were on the tires you took off the car. If they were well worn you would not have as much rubber between the rim and the road. The new tire has more tred, therefore more rubber between you and the road. It will have a different feel. I have noticed this every time I put new tires on my car. Think about why people put lower profile tires on their car. It reduces the amount rubber between the tire and wheel thereby reducing the any flex between the tire and the rim. Try them for a couple of weeks in a lot of conditions like on curvy roads and rough roads to see how they do.

keep us posted and good luck on the issue

I wonder if those tires are one way directional tires and if it was install reverse? I wonder and if it was balance correctly. I have own plenty of pilot sports and never had an issue except for tire wear.

The tires are not directional.

So i went to Costcos to have them look at the tires and they unmounted and remounted and say they are fine. Of course, they blamed the 36 psi and jacked up the pressure all the way up to 48 psi.

Problems persist

what should be my next step, take them back to Costco and just return? Would they even have my old tires with them anymore
or go to my dealer and have them look. I wish I had stuck with dealer directly, would have paid more but would have saved this headache

Stores are still responsible for the job being done correctly. I had another car once that someone on a test drive could feel the shimmy while driving. At the very least you may need to get an alignment perhaps or see if a caliper is hanging up, but whether it's another set of tires or a different brand of tire, your answer should be from Costco.
You are correct from an earlier post, the same tire from MB would only cost more and what would that serve to show?
Also, regardless of what psi you run at, at least show them the fuel cap door with the factory recommended tire pressures.

GlE John,
the sticker on the fuel door is inaccurate.
The sticker on the door —that is the correct one…

Got it, it's all subject to change and updates. That's why I said "at least show them..." The point was that using recommended tire pressures isn't an excuse for using the vehicle manufacturers psi value.
Anyone running into that with a tire installer will need to go "up the ladder" to get the problem resolved where the tires were purchased- manager/owner/corporate customer service.

I have no experience with the Michelin Premier specifically, but here are a couple of things to consider with tires in general.

• When putting on new tires, the car should be aligned at the same time or at least have had the alignment checked recently. Did Costco do an alignment or just mount the new tires? If they did an alignment, then they may not have it aligned properly. I had to get alignments fixed after a shop screwed it up.
• As mentioned above, brand new tires have more flex. First of all the rubber is new and hasn't hardened yet as your old tires, and the increased tread depth vs your worn tires also causes more flex.
• Tires need up to 500 miles for the lubricants from the mold to wear off and the different layers of the tire to start working together properly and for the tire to develop maximum grip
• Tire pressure should be chosen based on the load. In the US the door sticker only shows what's known as the max load recommended tire pressure. That's to be used if the car is fully loaded with passengers and cargo near the rated gross weight. The fuel door sticker has additional tire pressures for other load scenarios. Primarily what's known as normal load recommended tire pressure for when the car is not fully loaded as in how you typically drive on a normal day. These pressures are lower than what's on the door sticker.

As for shimmy it's most likely due to the wheel weight fell off or not in the correct spot when it was balance.

The OP has not stated what wheel size is on his vehicle. Assuming the 19" wheels, the current Michelin Premier for the ML is the Premier LTX DT (different thread). The previous version did not have the DT designation. The DT replaced the previous version about 2 years ago. I have run both on my ML - the DT is currently fitted- and I have had none of the symptoms the OP described. The DT is wearing much better than the previous version. I run 35 psi. I had problems with Costco tires in the past and quit buying them more than 10 years ago. I order from Tirerack and have them installed locally.