OK, I am a little new to this game, but shouldn't tire size be pretty simple? I have destroyed my first Bridgestone, so I decided to get a new tire for my KX-250. I like the tread on the Michelin, so I bought one. I bought a 120/90-19. I had a 110/90-19. I thought this would be a wider tire. It's not. It is thinner. The salesman assured me it would be wider. What's up? Should I run this tire? I can keep it for the 125, so it would not be a total waste, but I am still confused.