Final answer:
Janessa really traveled 25,459.8 miles on the new tires.
Step-by-step explanation:
To determine how far Janessa really traveled on the new tires, we can use the ratio of the tire sizes and herodometer reading. The ratio of the new tire size (P250/85R21) to the original tire size (P230/85R18) can be expressed as 250/230.
To find the actual distance traveled, we multiply the herodometer reading (23425 miles) by the ratio, giving us (23425 * 250/230) = 25459.8 miles.