Running a 110 tire on your 250F to get more traction? You might be running the wrong 110-there are two, the 80 percent height and the 90 percent height. The 110/90-19 tire is designed for the 2.15-inch-wide rim of a 250 two-stroke/450, and spooning one onto a 250F's narrower 1.85-inch-wide rim will actually squeeze it which increases the tire's diameter (raising the rear of the bike 12 to 15mm-and that's a lot-which affects the bike's geometry and weight balance), puts more crown radius on the tire (resulting in a "sharper" bend and about the same contact patch of a 100 tire) and adds unsprung, spinning mass to your nimble little thumper! If you want to run a 110 tire on your 250F MXer, run the 110/80-19. And obviously if you ride a 250 two-stroke or a 450, stick (pun intended) with the 110/90-19.
Got a Trail Tip? Send it and some pictures to karel.kramer@sorc.com, subject: Trail Tips.