Hi Tony, looking at that website (
https://www.wheel-size.com/size/volvo/s70/1997/), it seems a 215/45x17 is fine -
215/45ZR17 91W 7.5Jx17 ET38 5x108 2.5 / 2.3
And looking at this site (
https://www.tyresizecalculator.com/c...rim-size-chart) I could even go to a 205, but I think that would be pushing it tbh - I'd rather get some 17x7 Comets if I was going down that route.
edit - I fitted 215/45x17s to my black V70R, but they were on 17x7 Propuses, so the offset would have been 2mm different as well, as has been said.