Michelin PSS - Tracking - Unstable

[supaer]

So after my burnout failed from my other thread, i didnt manage to do one which is a shame but oh well saved the embarrassment.

Anyway i popped down to the lovely chaps at wheels in motion in Chesham and had 4 brand new sexy Michelin Pilot Super Sports fitted onto the 63. I also had the tracking done, the only thing that was out was the front toe which was corrected.

I asked the chaps to fill up the tyres to the 4 people plus luggage pressure setting as i am driving down to italy in two weeks and will have 3 people and luggage the whole way.

Anyway on the motorway with just me the car feels slightly unstable, for example going over a small bump you can feel the car jump slightly and also at certain speeds a bit of movement in the steering wheel, a bit of free play you would call it. No wobble or vibration just a bit loose is how i would describe it. Only over certain speeds though.... I am wondering if this is to do with the higher pressure in the tyre of if something else may be causing this.

Any help would be appreciated. I am going back to Wheels in Motion to get the silver weights changed to black as they ran out in 1 week so i will tell them when i am there, however just wondered if anyone had any suggestions.

 

[C240Sport97]

MPSS need at least 500, and preferably 1000 miles to settle down.

as you were driving alone, but will full load pressures, the car is over presssured and will feel skittish

 

[Palmball]

Tyre pressures - put them to the right level for your load now and the increase when (and only when) you need to.

 

[F1BHP]

Yes the high tyre pressure would cause it to be a little jumpy but also I have found the softer sidewalls of the PSS also give a little wandering feeling, but grip if the payoff.

 

[C36fan]

MPSS need at least 500, and preferably 1000 miles to settle down. as you were driving alone, but will full load pressures, the car is over presssured and will feel skittish

so the rears only good after 40% worn ?

 

[camerafodder]

Tyre pressures - put them to the right level for your load now and the increase when (and only when) you need to.

^^^This^^^

Tyre pressure specs are there for a reason.

 

[BIRMA]

MPSS need at least 500, and preferably 1000 miles to settle down.

as you were driving alone, but will full load pressures, the car is over presssured and will feel skittish

I have put them on two cars now and you are spot on there for some reason they need 1000 miles on them before they really show benefits.

 

[supaer]

Really, they need time to settle in?? i had them on my m3 and the side wall looked a lot fatter on the c63 they look a little skinny. i didnt know they took 500-1000 miles run in!! wow!

So it would be the fact that the pressures are a for a full load and the car is not full atm is why is feels a little loose and jittery on the motorway??

Thanks for all your help guys!

 

[supaer]

Really, they need time to settle in?? i had them on my m3 and the side wall looked a lot fatter on the c63 they look a little skinny. i didnt know they took 500-1000 miles run in!! wow!

So it would be the fact that the pressures are a for a full load and the car is not full atm is why is feels a little loose and jittery on the motorway??

Thanks for all your help guys!

 

[BIRMA]

I can only go by my personal experience with them, first of all on my Boxster, first thoughts were I've ruined the ride on this car but after 800 miles the ride improved in so far as not as jiggly I did check tyre pressures etc and I'm sure it wasn't just a case of getting used to the ride it did change. Second my VW Phaeton which is a barge no other word for it but again after about a 1000 miles the ride just seemed to be smoother and cornering more comfortable.
On both cars the most significant change was tyre noise compared to the Bridgestones on my Boxster at 70 MPH with the hood up you could listen to the sound system on the Phaeton which is silent anyway but on concrete roads there is significantly less noise.
Call me an anorak but I bought a phone app decibel meter and noticed at 70 there was an overall reduction of about 2 decibels with the Michelins.
I would hasten to add these findings were me just tooling around but it convinced me.

 

[st13phil]

As others have already mentioned, over inflated tyres will make the car feel light and skittish.

Also, new tyres - any new tyres, not just Michelin PSS - will initially feel like the car is "on tip-toes" for a while until both the mould release agent wears off (50 - 100 miles) and the tyres start to wear and give an even contact patch that matches your car's suspension geometry (anything up to 500+ miles).

Finally you were used to the feel of your car on old, worn, rubber which will always give a heavier, slower, steering feel compared to less worn tyres. Personally I'd just set the tyre pressures correctly and drive it.

 

[-Ian]

Yup I fitted new tyres to the back of my car. F1 Asymetric 2's. 275/30/19

When driving home I thought I'd made a massive mistake as the car was all over the place . Now 1,000 miles and 1mm of tread wear later they are performing fabulously well

 

[C240Sport97]

so the rears only good after 40% worn ?

I have put them on two cars now and you are spot on there for some reason they need 1000 miles on them before they really show benefits.

I had MPSS fitted on my GT3 about 2 years ago.

when I first drove it, I was convinced something was wrong with the car.

after 11k miles, the rears are at 5mm and the fronts at 6.5mm

MPSS don't wear quickly.

 

[G.P]

I asked the chaps to fill up the tyres to the 4 people plus luggage pressure setting as i am driving down to italy in two weeks and will have 3 people and luggage the whole way.

Anyway on the motorway with just me the car feels slightly unstable,

What did you have on before, as Mich do have the softest sidewall, on a motorway comments made so far are all incorrect as you won't notice in a straight line light steering or the car been skittish through overinflated tyres. Your either experiencing the butter soft sidewalls which will never improve or tread block movement as you now have 7mm which will improve as the tyre wears.

MPSS don't wear quickly.

Hence their lack of grip compared to others when on the limit..

 

[C240Sport97]

Hence their lack of grip compared to others when on the limit..

if you mean Cup tyres, yes.

otherwise, no.

 

[supaer]

I had MPSS fitted on my GT3 about 2 years ago.

when I first drove it, I was convinced something was wrong with the car.

after 11k miles, the rears are at 5mm and the fronts at 6.5mm

MPSS don't wear quickly.

I am also convinced that something is wrong with the car. However the only things that have changed are the front left toe was adjusted slightly which cant be the cause. I had the MO Conti's on before and i know they are a harder compound.

I hope that the butter soft side walls will not give this jelly movement sensation for much longer!!!

I will get the pressures adjusted in two weeks when i go back to wheels in motion and get them to check it again on the tracking machine.

Slightly disturbing feeling when you are doing 90 and a small bump in the road causes the wheel to move ever so slightly in your hand. I just like a solid feel which i would have thought i would have got with the PSS's.

I hope that if i do the pressures and wait a few more miles it will sort itself out.

Its not dangerous is it, the feeling i am getting?

THanks all for your input!!!!

 

[G.P]

I had the MO Conti's on before and i know they are a harder compound.

I hope that the butter soft side walls will not give this jelly movement sensation for much longer!!!

I will get the pressures adjusted in two weeks when i go back to wheels in motion and get them to check it again on the tracking machine.

Slightly disturbing feeling when you are doing 90 and a small bump in the road causes the wheel to move ever so slightly in your hand. I just like a solid feel which i would have thought i would have got with the PSS's.

I hope that if i do the pressures and wait a few more miles it will sort itself out.

Its not dangerous is it, the feeling i am getting?

THanks all for your input!!!!

Conti have a slightly firmer sidewall and a softer compound.

If it is the soft walls I'm afraid they will never get any firmer, but I still suspect your feeling the tread block movement, unfortunately new tyres never do grip as well as worn ones in dry/damp conditions.

I'd check the pressures yourself, your know for sure then.

If its the new tyres then no its not dangerous, just a very off putting feeling of which has caused me to disregard many a soft wall tyre, I have a collection of Mich. tires in the shed..

 

[Simon_M]

Change the pressures now man, what are you complaining about?

It's like you've set the a/c to 16 degrees and are complaining it is too cold but you will turn the temperature up on your next journey.

Correct the pressures now, you'll probably shag the tyres otherwise.

S

 

[Deleted member 37751]

What is the exact difference in psi here? Between single occupant and being four up with luggage?

Got to say I've never ever had the problems the OP has and if in doubt (with any vehicle) I go with 40psi. Surely the tolerances aren't that fine?

 

[supaer]

Why would they make soft sidewalls that give the feeling of unstableness.
I didn't experience this on the M3 or my 911.

I am keeping the pressure to this setting as in two weeks I am taking the car to Italy with 3 people and a lot of luggage and don't have a spare tank of nitrogen in my garage to top up etc.