Decided on getting a set of 20'' Stormers for my 05 Vogue but getting conflicting advice on tyre size from suppliers.
What the correct size to go for?

255/50/20 on a 8.5j rim...

scarey wrote:

255/50/20 on a 8.5j rim...

MMM....
confused now.

Been quoted on either 275/40/20 or 275/45/20

so 255/50/20 would be for a different size rim as the two listed above?

Rim size should be the same, in the manual for the L322 the tyre size for a 20 Rim is 255/50 R20. Possibly you are being quoted for RRSport tyres. I think their rim size may be the same by the offset is different and they usually have the lower profile tyres

They'd be for the wider 9.5j rim on the Stormers...

I'd suggest 275/45 as a minimum unless you like having half empty arches. Even better, push up to 295/45's (closer to the stock 255/50 diameter as well)

the 2 sizes you have quoted are for RRS and their wheels are 9j or 9.5j size rims ...

these can be fitted onto the fullfat but the speedo will be out and members have remarked that the wheel looks smaller in the FFRR wheel arch...

Right....
Slightly more complex this than I thought lol
Fear you are all correct and I am being quoted for a RRS wheel. Don't like the sound of the speedo being out etc.
So question is - can you even get the Stormers in 8.5J variant?

cant get stormers [afaik] but you can get supercharged wheels ...

Never been a fan of RRS wheels on a FFRR, as has already been pointed out - with the correct tyres fitted to the Stormer style wheel, they do not fill the arches properly and look a little odd - dare I say, look cheap...

...also, the Stormer style is copied by many non genuine LR/RR manufacturers and are unlikely to offer the same quality / strength as genuine LR. Although it concerned a different style (20" 7 Spoke) - once had the opportunity to compare genuine / non genuine alloys with each other and the 'copy' was almost half the weight of a genuine LR wheel.

Personally - I would only choose a style originally intended for the L322 by those who make them - and for 20" alloys = 255/50/20 tyres

All points made taken on board.
No really wanting to pay LR retail prices to be honest
Suggestions on where to source suitable rims would be greatly appreciated.

There's no need to pay LR retail

Have a look at what Dan has posted (site sponsor) as he has some good deals for LR 20's with tyres.

If you buy elsewhere make sure the rims are original

Obviously eBay is a good place to start - as well as the guys on this site.

I once got a set of brand new out the box genuine 20" alloys (no tyres of course) via eBay from another forum member full fat not diet for less than £500 - haven't heard from him in a while but might be worth PMing him to see if he knows of anything as he used to deal with various parts for Range Rovers.

Providing you are patient - you shouldn't need to pay anything like retail money