What are 25" wheels? The old (and mostly useless inch designations) would be 28" for most road bikes and 26" for 650c.
Contemporary bikes use 700c (which is XX x 622). Some Tri bikes and specialty bikes (designed for VERY small sizes) use a 650c front wheel (which is XX x 571). Have a look at the tire and see if you can find numbers that resemble those. If not, what do you see?