Posts: 69
Joined: 10/25/2016
Location: Canton, OH USA
In your own opinion, does the tire size make a difference on a 125?
I got a 05 yz125 and the previous owner had a 120/80-19 tire on it. Just wondering what everyone thinks is the best size. Should i switch it back to the standard 100/90-19?
Whats the pros and cons of each.
Posts: 591
Joined: 1/1/2008
Location: MA, USA
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.
Posts: 1163
Joined: 5/6/2009
Location: Coventry, GBR
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.
www.90smotocross.com
Instagram - @90sMotocross
Facebook - 90s Motocross
Posts: 446
Joined: 12/8/2015
Location: Orlando, FL USA
Posts: 4257
Joined: 9/21/2011
Location: Sacramento, CA USA
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.
Posts: 645
Joined: 5/18/2013
Location: Driggs, ID USA
Posts: 6747
Joined: 11/30/2013
Location: Portland/Los Angeles, CA USA
Posts: 1278
Joined: 8/4/2016
Location: Twin Falls, ID USA
Edited Date/Time:
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
Posts: 538
Joined: 11/24/2014
Location: Hartland, MI USA
Posts: 2462
Joined: 7/3/2009
Location: riverside, CA USA
Posts: 751
Joined: 10/29/2007
Location: Yorba Linda, CA USA
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...
