New tires - not happy

[Livewire]

Yesterday I finally replaced my Michelin Pilot Sport a/s with Yokohama s.drive on 2001 CLK55. The Michelins were great tires, but finally burned through the rear and did not want to pay for new ones. The s.drives were recommended by the tire store. Now the car feels a little sloppy at higher speeds or when agressively cornering. Almost feels like the back end is floating. Anyone know if it is just the difference with the quality of tire, difference of having tread again, or would it help if I increased the tire pressure. They were at 44 psi yesterday when warm. It was also 100 degrees here if that has any effect. Thanks for your help.

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[Jons95c36amg]

Your tires must be overinflated. Measure when the tires are cold(in the am before driving). It should be 32psi front and rear.

[HighEndOne]

My 2002 CLK55 has a chart in the gas door with the proper pressures. It will list two scenarios... low speed, light loads and higher speeds, fully loaded.

The rear takes more than 32 PSI for sure. And use an accurate pressure gauge when you check the pressure.

[SoCalCLK]

I run 34/36 psi cold. 44psi in 100 degree weather is asking for overinflation.

[Livewire]

Will overinflation cause the floating sloppy feel? I did look at the gas tank door, but was not sure if that number was dealer recomendation to maximize efficiency, but might sacrifice performance. Will a lower inflation such as 32 give you better traction? Thank you for your responses.

[HighEndOne]

Too little pressure is trouble. If a tire is underinflated for the load it is carrying it will heat up and eventually fail. That's partially the cause of all those Ford Explorer roll-overs on Firestone tires several years ago.

On my CLK, which is like yours, with the standard 17" size tires and wheels, I run about 36 in front and about 42 in the rear, cold. The tires are Michelin PS 1's (the originals).

There is no float to it at all. It sticks to the road at high speeds.

I can't say too much about the new tires you bought, I have no expeirence with them, but if the sidewalls are less stiff than the prior tires, they will feel less crisp and stable.

[s4avt]

Damn, I am at 28psi... i need to get some more airs...

btw, I recently went from Micheline Pilot Sport A/S to PS2 on the front and Goodyear Eagle A/S on the rear..

and I am loving it!!

[Jons95c36amg]

Originally Posted by HighEndOne

Too little pressure is trouble. If a tire is underinflated for the load it is carrying it will heat up and eventually fail. That's partially the cause of all those Ford Explorer roll-overs on Firestone tires several years ago.

On my CLK, which is like yours, with the standard 17" size tires and wheels, I run about 36 in front and about 42 in the rear, cold. The tires are Michelin PS 1's (the originals).

There is no float to it at all. It sticks to the road at high speeds.

I can't say too much about the new tires you bought, I have no expeirence with them, but if the sidewalls are less stiff than the prior tires, they will feel less crisp and stable.

42 cold pressure in the rear is too much. Mine is at 32 and it wears evenly meaning its at the right psi. Also traction is worse at 42.

[j-mo]

I was wondering about tire pressures a while back and still am since there are many different opinions. In searching the forums regarding pressure for the 208 there were several folks claiming that the gas door pressures are not correct and that the tires don't wear evenly because of it.

Here's one such post -
http://mbworld.org/forums/showthread...=tire+pressure

When I got my CLK55 a couple weeks ago my rears wear low, around 22-24. I followed what's listed in the post above going 38 front and 35 back. I have Pilot Sports on stock 17 AMG wheels. Car feels great but noticing bumps can be a little more jarring which I guess is expected as the tires bounce harder off bumps with more pressure.

Also, with the warm summer whether I've heard it's good to have 3-5 lbs. more than normal to help get better gas mileage.

Jury is still out for me. Might try 36/34 soon...?

[Livewire]

I think the problem may not stem from the tire pressure, but the tires themselves. I found these reviews at tire rack:

"Con's: Sadly, the tires have the worst reponsiveness of any I've ever had. There's a *very* definate lag between steering input and reaction. At freeway speeds a quick jerk of the wheel to zig a bit will make it very apparent. Also, when doing high-speed cornering it feels very unstable... almost like the tires are trying to squirm... (if that makes any sense at all :P) While I can take the corners faster with these tires than I could the OEM one's, it's a scary thing; even taking an overpass in a standard freeway interchange at the standard 70ish has the tires feeling squirrely."
and
"After too many miles on the OEM run-flats, I am trying the Yokohama. I was immediately pleased with the obvious reduction of noise, the smoother ride and the traction. However, I had been spoiled by the stiffer sidewall of the run-flats so much that the Yokohamas just feel spongey. I really need to set the car for turns and there is a noticeable increase in understeer. I am trying different pressures but have come to no conclusion yet.
I would recommend the tire for a passenger car and not for someone who drives "spritedly"."

[AMGOODNESS]

i run 38 all the way around. sometimes i run 38 front and 36 rear. tire pressure is based on the size wheel and tire you run and is very car specific. if you really want to know ask a tire expert like tirerack what you should be running.