I started with 38 psi in the Jeep and finally ended up at 40 psi, and have just as much traction as they did at 32 in the wet. However in snow, sand or offroading you may want to drop back to 32/34 range. My Michelin HydroEdge on the Magnum actually have noticable better traction at 40+ PSI in the rain then they do at 36 psi for some reason. The reason I started out with 36/38 psi is we have a lot of brick streets here in town, and they are about the same as driving on cobble stone streets in Europe. I wanted a little quiter and smoother ride, but it wasn't that big a difference in the ride for the difference in the tire preformance.

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91 MB 300D 2.5L Turbo. Her's

05 MB E320 CDI. Mine