Hello, I have a bachmann train from when I was young and I'm trying to get it going again to have around the Christmas tree this year. I'm trying to figure out what what scale my trains are? Also do the trains all take the same size tracks or is there different sizes? Also I'm going to need tires for my engine as the old ones were dry and cracked, can I just find a proper size o-ring or is it easy to find them online? Thanks in advance.