[kens_74_911s]

Ford Focus used the 4x108 bolt pattern. 108mm converts to 4-1/4" so that may be another way to search. ET is offset dimension from the center line of the wheel if the mounting face on the rim was dead on center the ET would be 0
So your et 15 outs the mounting face 15mm toward the outside of the wheel.
et 36 moves it out even more THus tucking the rim inward more.
et 52 like on late offset 944 and Porsche boxters etc puts the mounting face outward even more. Later cars and FWD cars run the hubs further outward for more bearing support and to fit ABS. so they need to run higher et to tuck whe wheels back under.