I've never looked at bicycles Walmart sells on-line. I buy tubes and cables (they sell a repair kit that has brake and derailleur cables cheaper than I can buy the wires elsewhere; I buy them for the wires.), the jumbo Slime patch kit (in Auto), cleaners, lube.... Disappointed they had only a 38 in 700c tires I was attracted to the bicycles with large '700c' tags hanging on their wheels, wheels that looked like they had tires much skinnier than 38. Some had 25s.

A rim that can accommodate a 25 as the smallest tire can accommodate a 38, so maybe one could use them, but I don't think the rider who wants a 25 will be happy with a 38.

Based on their statistics, that's probably a very safe assumption. I recall reading the president of Huffy saying the average lifetime mileage of their bikes was about 75.

And I suspect we've all known people who are inclined to throw away the whole bike when they get a flat tire.

sadly
i would bet even half of bike shop bikes often see less than 100 miles use
over their life time

i have had mare than one person say to me
when i worked in a shop
i got my bike about five years ago and ive never really ridden it so i guess its time for a new one

I picked up a tube at Walmart this afternoon. I remembered to check out the bicycles on sale. They had a Men's Schwinn Varsity 1200 with 700x25c (sic) tires. It was on the upper tier, hanging, not literally on the floor, in case this is what you meant.

Schwinn Varsity! there's a blast from the past. Would anyone buy a bicycle because it is a Schwinn Varsity these days?

My LBS was able to get a cheap clincher wheel; Low flange hubs, alloy rims and 36 straight guage spokes complete with QR skewer for less than $50!! Just make sure that you get the wheel retensioned and trued. I had to get a quick replacement wheel for my son a few days before he went to Scout Camp and the LBS came through!

But it's not true. Bike tires are basically round in cross section, so a wider tire will have a larger diameter.

read the OP's question, it was about tire width and rims, you've relating it to tires only, so what your'e saying is correct, but not in relation to the original question, my quote above makes no sense without context which was the relationship between tire with and diameter, referring to the 27" / 700c as I mentioned in the missing line of my quote, anyway, the original topic got way of course relating to Whale blubber and 2012 Ford Focus issues, bit like this reply...

Don't know if I would expect, or be distressed, if my Wal-Mart bike didn't outlast the tires.

And, our Wally-World does carry more than 700s than just 38, but nothing I would ride any longer than it would take to get a real tire.

If the OP is talking about rebuilding wheels and installing wider tires on his Grandis so that he can use the bike for "gravel grinding," to use his term, he might be better off finding a cheap used mountain bike instead. Every Grandis I've ever seen was a professional-level Italian bike. If the bike is in good shape, it would make sense to keep it that way.