Tire Size on a 125

You’re shooting yourself in the foot with a 120/80-19 on a small bore. You will absolutely notice a difference in power between the standard size and a tire designed with a 450 in mind. Plus, you will also notice an improvement with lean-in entering turns. A bigger/taller tire wants to stand up more it seems, where the standard tire will lean over with ease and arc the turn better. I suggest a Michelin Starcross 5 Medium or Soft 100/90-19. Pirelli 32 or Dunlop Mx3s would be my 2nd choice.

A YZ125 with a 120 rear on will probably feel like an 85 in anything except hardpack conditions. A 100 for sure, but can get away with a 110 on a quick yz125 or husky/ktm.

Don't think about anything other than a 100.

My (used) '05 YZ125 came with a 110/80-19 with some aggressive (low) gearing. I liked it, so I got another one (MX51). Don't think Dunlop offers a 110/80 any longer, so I'll be going with a 100. Ride mostly off-road and hardpack throughout the year with this bike.

100 is the width you want for the 125.

I run 100/90 on KTM 125.

Run a 110, it will stick in ruts and flat corners.

Pcp252... that’s funny that a 120 was designed for a 450 when I ran 120’s before there were race 450’s... try again young buck

We run a 100 on a 250F........

KC

100

100/90-19 on a 1.85 width rim! Only way to go

Some of the 250F's can pull the bigger tires/2.15 rim, but not the one-two-fiver's...