Is this even an option? Or would i have to have some type of conversion kit. I have a 20" Haro mini that my son races with but the tires just seem too big on it. He is a little guy. An 8 year old in a 5 year olds body. I was wondering if I could swap out the tires for some 18" wheels and tires. Would the be a bad idea, make the bike slower, not even an option? still kinda new at the bmx stuff so any info or input would be greatly appreciated. Thanks!