Does the smaller the back hole shots make a difference I notice racers have tiny hole shots in the back and mine are HUGE!! does it make a notable difference to anything?

 

If you are talking about MX racing, they run 18" tires in the rear........ Smaller rear tires will handle better because they lower the center of gravity, they will also give you more low end off the line......

But if you ride woods or trails the 18" will be too small and you will lose ground clearance. They are really only used for MX racing. Even in the woods XC racers usually run 20" or even, 21" or 22" for more ground clearance.

 

The small tires are also less rotating weight, so better acceloration, but a loss in speed, I also think they hook up better than taller tires, and you don't have to worry about sidewall flex or roling a tire off the bead.