Ever since i bought a used 2005 S60R there seems to be many problems.
1. humming from underneath the car in rain.
2. tire rub on plastic shield, when i turn more than 3/4 of the steering wheel.
is there anything i can do to prevent this. its annoying to hear the rubbing.

 

The humming noise in the rain, could be a mild case of rain squeal. Usually it's a loud squealing sound, Hence the name... If that is the case, simply do a resonator delete by Replace the resonator with a straight pipe. You can tell once you have the car in the air, if there is a scorch mark on the drive shaft from the resonator bowing up and making contact. Rain Squeal is VERY common amongst the R owners, myself included. Search on SS to read lots more about it. Also make sure your exhaust bracket has been removed. That can cause thousands in damages if it catches anything on the road by shoving your exhaust into the drive shaft and destroying both. Again search "exhaust bracket of death" on Swedespeed.

The tire rub issue your having is something ALL P2 R's have to deal with. The OEM Pegasus wheels we have needed to fit over the Brembo's so were stuck with a turning radius about as large as a aircraft carrier's and wheel rub. First, check your bump stops to see if there bad. This will not fix your problem but will lessen it by taking away how far you tires will turn side to side. What most have done, is either stop turning the the steering wheel to full lock, or installing 5mm spacers on the fronts. That will fix all together for you as long as your bump stops are in good shape.