My 2011 FFRR SC came with 255/50/20 tires. If I wanted to go a little wider but maintain the same height would I go to a
265/50/20?? Thx

255/55 means the sidewall is 55% of 255 mm which is 140.25

265/50 is 132.5 so that's quite a bit smaller diameter than the standard setup, so your speedo will be out a bit.

Technically the car would accelerate faster but have less of a top speed.

There are sites on the internet that will provide all the info you need ;

http://tire-size-conversion.com/tyre-size-calculator/

Or this gives a bit more info

http://www.willtheyfit.com

 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

Take a look at

http://www.willtheyfit.com

Will help in determining the correct rolling radius of the new tyre. Bear in mind you will still need to check that it doesn't foul the arches/fenders or any suspension components

Sorry mjd didn't notice you posted it......  There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

275/45/20 is probably the closest in O/D

Would there be insurance implications going away from non-standard?..Just a thought. GONE 2010 Facelifted 3.6 TDV8 - Stornoway Grey + 22" Overfinch Olympus
HAVE 1999 Discovery 2 GS 4.0 V8 - Silver - Off Road Toy
GONE 2013 L405 4.4 SDV8 Vogue. Black with Silver roofline and 22" s
HAVE 2015 Jaguar XF.

You need to ask your insurance company - always better to tell them what you are doing - that way you won't get a nasty surprise in the event of a claim.

My company (NFU Mutual) tend to be fairly relaxed about modifications which are 'non performance enhancing', this would be an example.  2006 (56 Reg) 4.4 V8 Vogue In Bonatti Grey (Gorgeous!!)

Yes, as above, I'm not an expert in this matter, but I'm not sure it's type approved with different sizes of tyre on.......

Definately way for the insurance company to get out of paying up if you haven't told them. 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

We'll me I never new the side wall part of tyre dimensions was a percentage. Learn something every day. I don't know what I thought it was but never thought it would be a percentage.

You Learn something new every day (unless you are a politician)  2006 (56 Reg) 4.4 V8 Vogue In Bonatti Grey (Gorgeous!!)