Max Wheel offset?

Does anybody know what the max wheel offset is that you can put on a 1989 cabriolet? I'm looking at 15" x 8" with an offset of +20. Trying to understand if this is going to rub and or scuff arches and inner wheel Wells when on full lock. I have JOM coilovers too. Car is totally stripped just now getting ready for overhaul and paint, so no running gear on the car right now it's on a rotisserie. But I'm trying to order wheels so when I get it off she has some shoes to sit on. Any ideas…? Was originally looking at 15" x 9" but think that will cause probs…..so settled on the 15" x 8" but now looking to figure out the offset…… Any help is appreciated. Thanks

There was some discussion within the last couple of weeks on wheels

https://vwgolfmk1.org.uk/forum/index.php?page=topicview&id=chat%2Fgeneral-chat_3%2Flowering-tyre-choice

This might help… Alloy Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit