Okay, googled and found info on tire size designations. http://www.webbikeworld.com/Motorcycle-tires/tire-data.htm says that for a tire that is 130/90-16, "90" is the aspect ratio of the tire width * height / 100. So practically, if the 130/90 were an 130/70, would that mean the tire is not as tall? I'm looking to replace my 110/100-18 rear with either a 100/90-18 or a 120/80-18. Is the 120 wider but not as tall as the 100? Which one would generally be better? Thanks, you guys rock.