Wheels from Volvo V40 Cross Country on Volvo C70: compatible?

No, the centre bore is too small

Same 5x108 PCD, but the centre bore of the wheels from Volvo V40 Cross Country (63.4 mm) is smaller than the hub of Volvo C70 (65.1 mm): they will not fit without being re-bored by a professional.

Volvo V40 Cross Country2012–2021Volvo C701998–2006
PCD5x1085x108
Centre bore63.4 mm65.1 mm
ThreadEcrous - 12x1.50M12x1.75
Original wheels ≈6.5Jx16 ET52.5 ≈6.5Jx16 ET43
≈7Jx16 ET45

≈: width estimated from the original tyre size.

Before fitting the wheels

An identical hub is not enough: offset, width and diameter change the position of the wheel, and larger calipers can touch a smaller wheel. Original wheels often use bolts or nuts with a specific seat: keep the fixings intended for the wheel, with the thread of Volvo C70 (M12x1.75), tightened to the torque shown on its vehicle page. Finally, check that the size is among the approved fitments for your vehicle. This comparison is for guidance only: have the fitting approved by a professional.

And the other way round: wheels from Volvo C70 on Volvo V40 Cross Country?