Now this also applies to other models and other cars but if a 19" wheel is replaced with a 20, 21 or even bigger does the recommended profile of the tyre require changing to give the same TPM as the original. Sorry if this is a daft question

Yes, you should use a different profile to keep the rolling radius the same, otherwise the speedo will be more out, etc.

Different rolling radius to standard probably wouldn't affect the TPMs because that works by spotting increased drag on one wheel.

The wheels have sensors inside them for monitoring pressure. You can check and read tyre pressures using service menu. I have fitted 275 55 20 BFG KO2 AT tyres which increased diameter by around .9 of an inch. Speedo reading did not change still under by 4 kilometres per hour.

Interesting, I wonder if this might effect the warranty, I'll check with the dealers

I changed out my 22 inch wheels for some 20 inch so I could run some more off road orientated tyres. Now running 285/50 Coopers which makes the speedo exact. M16 SVD8 ,4.4 HSE with a few extras, Sold R50 , Wife SQ5 , BMW R1200GSW.

Which style 20" wheel did you go for IRBails? The 20" wheels were one of the reasons I went for the SE... I will run the Pirelli's mine came with until they need replacement, then swap to Pirelli Scorpion ATR's upon replacement. I used these on my Touareg and liked their on road / off road tread compromise. 2017 MY17 SDV6 SE

I kept my 22 inch wheels and purchased previous models 20 inch in Black, no idea what model. The deal with tyres cost me $1800 as there are more people that buy RRS for looks not function so most people want 22 inch and nobody wants 20 inch. M16 SVD8 ,4.4 HSE with a few extras, Sold R50 , Wife SQ5 , BMW R1200GSW.