It is also explained well by Buzby as shown below
When you change a wheel for a bigger one (and at the same time reduce the sidewall height) the rolling diameter does not remain the same, the software compensates for this to display the correct speed on the speedo.If you are going from 16" to the 17"x7J Ixion R Design wheels, the steering rack limiters do not need to be fitted (they are only required qhen 7.5J or 8J wheels are fitted due to potential rubbing issues). The 'Impulse Limiter' software application still needs to be downloaded to recalibrate the speedo though, as the wheels and tyres are not exactly the same rolling radius.
The two approved sizes for the 16" V40 rims are:
195/60R16 gives 800.0 revolutions per mile
205/55R16 gives 811.3 revolutions per mile
The 2 approved sizes fpr the 17" V40 rims are
205/50R17 gives 805.1 revolutions per mile
225/45R17 gives 808.2 revolutions per mile
See this link for the list of approved wheel and tyre sizes:
http://accessories.volvocars.com/en-mt/V40(13-)/Accessories/Document/VCC-499025/2017
Regarding the tyre sizes, if your car is a "zero road tax" low-emission D2 it should only be fitted with the 205/50R17 tyres. If it's not a low-emission D2, 225/45R17 tyres can be fitted as an alternative
It's all explained in the relevant page on the Volvo Accessories website:
http://accessories.volvocars.com/en-mt/V40(13-)/Accessories/Document/VCC-499017/2017
Note that I've had to go to the Volvo Malta accessories site there - Volvo UK and Volvo International have reworked their model accessories page system now that makes it painfully slow to use, and has also removed all the important information from view by the public. It now just tells you to check with your Volvo dealer for full compatibility information.