ok, so, the front wheels are 17" across, and i have found that the rear wheels are the same size as the front.
but i also did some math to account for the image's perspective distortion this time.
if we just use the width of the rear wheel (which the camera is centered on), the wheelbase does...
if tires are 32" in diameter then wheelbase is about 97". wheels may not be 32", but some quick math can give an estimate for other wheel sizes.
pic is scaled to 10 pixels = 1 inch if the tires are 32", length of green lines are laziness.