Vintage Dirt Bike Q & A

A while ago I picked up a tired but complete 75 CR125. (Yes my wife makes fun of my strays!)
It looked kinda odd, and turns out the oddity was an 18 inch front rim. It looked like it had been on the bike for many years.
What was the purpose of this modification? Dirt tack racing?
Just curious.

Could be but I think the term you want to use is 'flat track' instead of dirt. If you google it, you should come up with a lot of representitive bikes.

MX was a relative late getting the the USA. Prior to that most of the interest was hill climbs and flat track. Some relatively famous people came out of it. Joe Leonard was AMA champ before he went on to Indy and racing the jet turbine cars. I saw where Kenny Roberts, world champ, started off on a Tohatsu. I thought the class was 100cc but its been to long for me to remember and I wasn't really paying attention in the 1970s.

Rick