So if you go from stock 20" alloys to a set of 22" your speedo is off apparently and so far I haven't found out if you can recalibrate the speedo to take into account the bigger circumference of the new rims. Anyone got any info on this??

It is, but not to the point you would be excessively speeding or in accurate. I have 22's and my dash cam has live gps based speedometer onscreen, so I'm always comparing the 2 and they are not that different. What ever speed I'm traveling, the gps is reads lower by about 1-2mph. After 2 years I've never set a speed camera off yet.

What size are the tyres what are on now & the tyres that were on before,,you can check here & it will give you a reading,,remember their is a differanc in a new tyre & a used one also,,yo have 8mm of tread on new & can be down to 2 with used that will also alter speedo.
When I used to have hgv's I used to put worn tyres that had been re-cut & sent them in to be calibrated then when I put the originals back on the trucks would go 61-62mph instead of the 56 it was reading on the clock.

http://www.kouki.co.uk/utilities/visual-tyre-size-calculator
Andy Andy.
21 Ford Ranger
Gone but not forgotten
Focus RS Red Edition
2015 RRS AB Fuji.
2014 RRS SC Santorini
2016 VW Amarok
2014 RRS AB Fuji
2012 RRS Red Edition Fuji
2015 Nissan Navara
2012 RRS SE Santorini
2008 RRS White
2007 RRS Santorino

Very useful site! basically instead of doing 60 I will actually be doing 62.5 on the bigger alloys/tyres. Not bad

plus your speedo will probably be more accurate with the slightly bigger wheels.Ive gone from 275/45r21's to 295/40r22's on mine & its out about the same as yours .

Andy Andy.
21 Ford Ranger
Gone but not forgotten
Focus RS Red Edition
2015 RRS AB Fuji.
2014 RRS SC Santorini
2016 VW Amarok
2014 RRS AB Fuji
2012 RRS Red Edition Fuji
2015 Nissan Navara
2012 RRS SE Santorini
2008 RRS White
2007 RRS Santorino