Replaced my old worn out Michi ps2s to new ones, 225/40-18 in the front (N3) and 295/35-18 in the rear (N4). Stock dimension.

The front is fine but the rear is really acting up baaaad, it feels like the tyres are too soft in the core, its a bit wiggly and bouncy and at higher speeds and long turns. A bit uneven road but good enough to do 170 mph+.

So I called the dealership and they said there shouldnt be a problem with thoose rear tyres. Will give michelin a call but I thought I'd ask here first. Any ideas?

I should add that I have 3 bar pressure in the rear (43.5psi).

/christoffer

 

often times you'll find the psm/abs lights happen after switching to new tires. it's as if the ecu needs to re-learn the new tolerances ( and usually does ) provided the tires are within the correct rolling diameters = frt/rear. i'd cycle thru a few times with starts/stops. if it persists, then next step is... sorry... if it doesn't persist, well there ya have it. it's not uncommon though. btw.. i would go 36/40 front/rear on ps2's

 

New tires have a mold release agent that makes them slippery for the first couple hundred miles. It should go away as they break in

 

thanks for the answers, I will try adding some more pressure and get a few more miles on them. Hopefully that will do the job

 

I hate it when the PSM kicks in when I'm doing 100+; so I turned my off completely. If you feel your rear is bouncy, lower the air pressure to 40; it will feel much better. My rears are at 36 psi.

 

Aren't the rears suppose to be 295/30-18?

 

Good catch dude!

 

I checked the specs -- hopefully, the OP just had a typo in the tire sizes. The rears should be 295/30-18 to match with the fronts (25" overall dia). Otherwise, if the rears are 295/35-18 tires, I believe they're 26.1" (about 1" too large). Couldn't this contribute to the PSM acting up?

 

...Agreed....I run 295/35/18s But with 245/40/18 fronts...

 

****, I bought the wrong size then I am now as I wrote above on 295/35-18 rears and 225/40-18 fronts, could this mess something up?

 

Yup -- that could be part of the problem. If you want to double check tire sizes, TireRack is an excellent online site (just enter in your car information). Of course, you can go to different sizes, but for our cars that are AWD, it's important to keep the overall diameter the same.

http://www.tirerack.com/tires/Select...3&autoModClar=

Did you really get the tires from a dealer (i.e. Porsche Dealer)? If so, you might be able to complain to them about it since they should have really known better. I'd think they would be willing to swap the rears for you. Good luck and let us know what happens.

 

Ok thanks for the tip, I must've just mixed them up when I ordered. I ordered online and I doubt I will be able to return theese.. Maybe this is a valid reason to try RWD conversion :P

 

Will this potentially damage something in my car? Even if I turn off psm?

 

I'll have to defer to the more experience people here who might have some experience with this. The only thing I've really heard of that could be of concerns is excessive wear of the front differential. Of course, handling and performance might change a little too.

As another suggestion, you could order a set of rears in the correct size, and just keep the larger rear tires for your next set of tires. If you're just changing the rears this time, chances are you will have to change both the fronts and rears the next time around. You could then just buy a set of fronts in a larger size to match with the current set of rears (like johnspeed) and you should be good to go. Just an idea.