I need 4 new tyres and thinking of going for 274x45x20 up from the origonal 40s. My question is what do I do with my spare? It's the standard 19 inch wheel and tyre ( not sure of size) but if I get a puncture is it okay to use. I've read about the fact that the RRS doesn't like new and old tyres on the same axle. any advise would be usefull. 07 tdv8 stornoway grey at home tucked up
x type jag work and back hack
x5 Gone - never fully loved or cared for
Disco td5 gone - saved a fortune on ear plugs
Freelander gone - one of the first and worst
early disco gone- A tractor in a fur coat.

Apart from the issue of speedo/insurance/modified vehicle spec from the OEM then provided you treat the spare as an emergency wheel and follow the speed/distance instructions you shouldn't do any harm

Running unmatched tyres on any 4x4 has been known to damage diffs, etc - hence the restrictions in the handbook and sticker on wheel  Wanted a Series 2 LR since childhood but previously owned MY16 Disco Sport HSE TD4 Auto, MY13 RR Sport Black Edition TDV6 Auto, MY10 RR Sport HSE TDV6 Auto, 2007 Freelander 1 Freestyle TD4 Soft Top, 2009 Freelander 2 GS TD4 Auto, 2007 Freelander 2 GS TD4, 2004 Disco 2 Metropolis Auto, 2002 Disco 2 GS, 2000 Freelander 1 SE TD4 SW

Still hoping for a S2 one day!

You could put a 255/55 on the 19in rim (assuming it's full size). That would bring your spare to 7mm of the diameter of the main tyres. As muddy says, if you limit any spare usage to the bare minimum required to get the main tyre sorted then you should be ok. But you really do need to keep speed and distance down to limit possible issues with the transmission. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

I was in the same boat, full set of 20 inch but a 19 inch spare, bit the bullet and got a matching 20 inch rim and tyre, it's not cheap but I think it's the only way to go especially if your driving long distances... 2008 G4 RRSport TDV8 current
2009 TDCi 90 current
2018 Discovery 5 HSE lux current
1994 Dakar current