Please help with 20" on 2008 4.8 sport

[GPSnV1]

I apologize for not searching first, but it is 4 am and I am out of it.

My wife went to the dealer last night at 8:30 pm and decided that if we were going to get a 2008 4.8 sport, that she wanted the honeycomb wheels with 20" tires. Her point of reference is our 2004 4.4 sport which has OEM wheels and tires that she likes, but dislikes the 19" wheels and tires for the 2008 4.8 sport.

Well, I woke up wondering about all the problems I would have with those 20" tires. Is it true that they only last 20-25K? How much do they cost to replace?

How do they handle heavy rain, snow and ice? I live in OKC which can have have rain - and hail and tornadoes but that's another story - and some snow and ice, but twice a year I have to travel 3-4K from OKC to TN, NC and at times VA, SC, GA and even FL. One trip in July the other in Dec/Jan.

Obviously I have seen all kinds of winter weather on the open road during the Dec-Jan trips. With these 19" tires on the 2004 sport, I always watched the weather channel closely to see if I needed to leave early or late and guess that now I need to be a psychic to make sure I can get over the mountain between Nashville and Chattanooga and the mountain near Asheville (NC), and so on.

And how do 20s do at high speeds? I mean above 100 mph? I don't consistently drive that speed, but I have been known to go over 100 on some of those barren stretches between OKC and MEM.

Thanks for anybody that happens to be listening on a holiday. I am due at the dealer this morning because I leave for a trip on Wed (return at 9 pm Sat) and Tues is already tied up. So if I'm going to get the benefit of buying at the end-of-a-slow-month for my dealer, then today is my best shot.