I was wondering what the numbers, for example, 100/110x18 mean. This is for motocycle tires but I was hoping somone might know.[img]i/expressions/face-icon-small-smile.gif[/img]

 

I think your tires is 110/100, not the other way around,right?
The first number is he tire width in mm, all tires are measured differently. The number after the / is height of the tire. That number is a percentage of the width. so 100 means 100% of the width is found in the height from rim to tread.
The last number (18) means it is an 18" rim.