I just bought my 2012 vulcan classic lt. It was new left over stock. I have put about 700 miles on it now. I noticed when driving down the highway I get passed a lot. So I decide to take my handheld gps with me down the road. My speedo is off by about 5 mph. So 60 is 55, 70 is 65. I have read where people have put on bigger tires and different pulley to bring the rpms down on the highway. Would a bigger tire correct the speedometer some too?? If so what size are you guys using.