I'm researching my options for a new set of winter tires for my 2006 Sport. I came across a couple of good deals on a slightly different size: 255 55 19 vs. the OE 50 series. Have any of you made this change and are there any opinions as to why this is not a good idea

Thanks for taking the time...

Besides the larger circumference (which may make your speedo marginally incorrect), the extra sidewall of the 255/55s would likely make your ride a bit more cushy, give you a smidgen of additional ground clearance and protect your rims better over rough / snowy / icy roads, while the contact patch with the road would be the same as the stockers. The tires will fit no problem - that's actually the stock tire size on Disco/LR3s with 19" rims and even Land Rover uses that size on the Sport (in mud terrain form) for its G4 vehicles. As winter tires, IMO the bit of extra sidewall of the 55s would actually be more desirable than the lower profile 50s, so I think it's a very good idea. You may even get some use of those winter tires for mild off-roading situations one day, since more sidewall and a grabby tread are always a better idea off road than the stock "racing slicks" summer Contis.  

Thanks for your reply and recommendation, this is exactly what I was looking for