What's the largest tire on a KDX250? 1993..

I have a 110/100/19 on the rear of my bike. Someone mounted up a 19" wheel there from a KX. It fits fine.

I would think you could go 130/80/18 without a lot of issue, but never tried.

Was just at the shop this week looking a tires. A Michelin S12 in 130 x 18" is just a hair smaller and lighter than a Dunlop 756 in 110 x 18".

I used to run a 130 Michelin M12 on my KDX250.

The Michelin 140 widths look quite a bit wider and heavier, but I didn't put it up side to side with their 130. The 140 might fit, but I think it is intended for open class bikes and probably would not offer any perforamance advantage for your 250.