Ticking/knocking noise from tires? engine? snow and ice?

have an 04 mountaineer and started to hear a ticking noise, speeds up when i do and slows down when i do. it drives fine steering wheel doesnt shake no wobbly feelings. at first i thought it was a flat tire but wasnt so i thought maybe theres ice in the tire but i keep in in the garage at night and it gets to be almost 40 degrees. for the past week i have heard it everyday. my husband just did the brakes and rotors and calipers ball joints tie rod ends and fixed a rear axle seal. unfortunately he's in the army and they took him away from me again so i have no help on this. we're in upstate new york and it does get to be well below zero most nights so maybe it could be ice, i don't know. i will be checking this question frequently so if you can help me but need more info just ask and i will edit. thanks so much in advance for any and all help!!