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Replacing woofers on Infinity SM155

I am wanting to replace both blown woofers on a set of Infinity SM155 speakers. I have found info that shows total of 8 ohms for the complete speaker. My question is what is the ohm rating of the woofer since I can't get a reading on the blown ones. 4 or 8 ohms ? The 15 inch woofer has a tag on it SM15-1. The midrange are 4 ohm and the tweeter measures 7 and change.

Thanks for any help.