I have both metzler marathon 888 on front and rear of my 17 ultra limited custom. 120/70/21 on front and 200/50/18 on rear. I've been running them at factory specs psi but believe those are for dunlop. I'm 240lbs and do ride 2 up and luggage about 50% of the time. I've noticed at higher speeds 70+ I get a wobble in rear. What would you folks recommend me to have my psi at? Had the bike looked over from harley dealer and everything is tight and in line. I'm almost positive it's my tire pressure.

 

The Metzeler website should give you pressures for stock tyres, including your rear. I'm a firm believer that they provide a starting point. If you are heavy, or very light, make adjustments to suit, say a couple of psi at a time. When we use non-stock tyre sizes it is our responsibility to get things like this right! So try a little experimentation to see if you can improve things.