This is the thing - cars make all sorts of noises, so a whine to me might be something else to someone else. My wife hadn't noticed it, but I had. Still hope it is a tyre thing.

Looking at other posts on here the whine gets very loud over a short period of time. Black MY2013 SD4 GS Auto, Wood Company Armrest, Freel2 sticker.
Gone MY2010 Freelander 2 Manual TD4.e S, Alaska White.

It would help if you were to check the tread depth on your Wranglers. If it's 4mm or less that's probably your cause (and maybe time to replace?) - if not maybe look elsewhere. But as said above, I would not expect bearing or diff noise to change with the road surface. Ex AA Series III LWB Safari - Gone
300TDi Disco (bought new - terrible car) sent back after 18 months
Freelander 1 Estate - leased, given back at end of lease
200TDi Disco (bought from a mate with 100,000 on the clock) - Gone
Disco 2 TD5 - sold and exported to France
FR2 TD4 GS - Gone
FR2 SD4 HSE - Now changed for a DS
New model ex-demo Evoque S 180 in white
Unable to order a new DS, so gave up. Now have a Volvo S90 Recharge.

I had worn Wranglers on mine and agree with the earlier posts. They become very, very noisy once they become worn. Mine were also worse in the cold. Like you I thought it was the early signs of diff failure!

Will need to get a depth tool thing but yes I will check them. Visually the look really quite good though.

Just had a wheel bearing done n/s rear. It was possible to hear the noise change on bends, ie left handers taken briskly possible to remove noise completely as weight came off. As soon as straighten up came back. Most noticeable 50-60, quiet at 70 for some reason.

It wasn't a whine, more of a grnn grnnn grnnn, errr wheel bearing type noise, which isn't helping much I know.

Worn wranglers will confuse you, from 4mm and from reading diff bearing issues I was certain I had the bearing problem so on my previous car I renewed with Pirelli Scorpions because of a tyre/wheel purchase and you wouldn't believe the difference, whine disappeared and stayed that way.

Bet your bottom dollar if you had not read about diff noise on this forum you would not have noticed it
I thought I could hear a wine with my car had my local dealers mechanic take it out for a spin & very words he told me stay off the forums (paranoia)

Oh yes, there's a lot I've read here that I wish I hadn't know about!

However, the noise is definitely there. It sounds more like a mouse sending Morse code than a constant whine so I'm at a loss. It started while I was on the motorway today. Went away when I dropped to 30.

Mines always had a drumming noise around 50, worse when the road is wet. When I changed from wranglers to general grabber AT's the noise stopped for about a month then came back. I read somewhere on here that the noise is from the large lugs on the tyres. Black MY2013 SD4 GS Auto, Wood Company Armrest, Freel2 sticker.
Gone MY2010 Freelander 2 Manual TD4.e S, Alaska White.

My 60 reg FL2 49k miles is developing a whining/wirring noise under load. Seems to go when you back off the throttle. Not gear or engine speed dependent. No steering vibration. Is this likely to be the dreaded rear diff bearing problem that I hear about and are there any other symptoms or something I should look out for ?

It could either be the rear nerside wheel bearing, this will get worse very quickly, or the diff, this will get slowly worse. Lift car and manually spin the wheel, you will feel it grating if the bearing is going.

Of course, it may be something else, low tyre tread is susceptible to increasing the noise on the FL2. Hope it gets sorted as painlessly as possible

I would be interested to see how you get on with this. Mine is doing similar but I have neither the cash to investigate right now or the ability to be without the car for any length of time.

Spoke to the LR dealer this morning who is going to get LR Assist to come out and have a look at it and advise on what to do about the noise. It sounded as if LR assist can approve warranty work to save me a trip to the dealer. Said also that if they deemed it necessary they would send for a recovery truck and arrange for a hire car. Sounds good so far!

Seems to depend who your dealer is I guess. If I called my local Morrisons LR they would just book it in and charge £120 for the pleasure.