Not saying this is the case, but practically all roads have a crown to them extending out from the centerline of the road. So, if you’re going down the road and let go of the handle bars and the bike begins to drift right, keep in mind, it may be due to the crown in the road and not necessarily your bike...some crowns being more pronounced than others.
Also, under-inflating tires may give a larger contact patch which would spread the load over a larger surface area...However, under-inflating your tires will also increase tire temperature which in-turn will speed up the wear of your tire ultimately shortening the life of your tire.
Manufacturers design tires to run at specific pressures for a reason. When you deviate from this, one cannot honestly expect a tire to perform as it was designed.
If you suspect that your tires are not aligned to each other or to the frame... locate some long fluorescent lamps, place one on each side of the rear tire making sure that the other end extends past the front tire. Use tape or something to hold the lamps snug to the rear tire and check if your rear tire is straight to the frame and in line to the front tire by measuring the difference from side to side. Adjust rear tire as required.
