rear brake disk size

Here is a guide that will help with this:

https://www.2carpros.com/articles/how-to-replace-rear-brake-pads-and-rotors

Also, the only way to know for sure which size rotor you have is to measure the current one or look the VIN up on a dealers parts system and have them give the specific part number.

However, here is the process on how to replace these from the manual. Let's run through this material and let me know if you have questions. Thanks

How to remove the rear brake drums on a Toyota Avensis TD estate 1998

Here is an exploded view of rear drake components. What is the problem that you are facing?

I'm trying to do this drum removal on a '98 Avensis...drum won't come off, even when screwing in 2 extracting bolts...Haynes manual says to use a wire hook to back off trailing shoe but can't figure this out...any advice appreciated...
Thanks