Oh, on knives, I usually carry a cheap ($10) kitchen knife from Wal-Mart or Target. That knife is practical for slicing apples and avocados and is easily replaced if anything goes wrong with it. They typically include a sheath which makes it practical and easy to store the knife.
When I think about it, it has been years since I went on a tour and carried an extra tire.
All I carry is a cheap made-in-China lock blade knife myself, it is extremely sharp though, with a titanium coating, but it cost me $20.
There is some cheap stuff you can get for bike camping that will work just as well as expensive stuff and you're not driving up the weight much by doing so maybe a few grams, in fact I've seen mess kits that cost a lot of money that weighed more. My mess kit only costs $10 from Walmart, called the Ozark Trail, it's made of stainless steel, it's lightweight, and I made it lighter by not carrying the pot, I just carry the pan and the lid, and I have a stainless steel cup that I cook stuff that would normally go into a pot, that cup also came from Walmart for $5.
I don't buy those dehydrated camping foods, those darn things can cost $8 and more, might as well eat out! There are YouTube videos on how to eat cheap while backpacking or bike camping.
When I first started doing this bike camping stuff I carried a spare tire, but I never had a flat not alone destroy a tire. I have since gone over to an even more flat-resistant tire called the Schwalbe Almotion, this thing is extremely tough, the only way I could destroy that tire is if a car hit me, but then I would have bigger issues than a tire. So I stopped carrying a spare, and I only carry one tube. I can fix all my flats on the side of the road, not a big deal. Since I don't carry a spare, and since I don't want to fix a flat on a loaded bike, even though the Almotion tire has a very high flat resistance to it, I installed a set of Clear Motion Rhinodillos flat strips, they're lighter than the Mr Tuffy and they are much more resistant to flats, I couldn't drive a tack through one but I could through a Mr Tuffy, plus the Rhinodillo has a soft edge that prevents the strip from chaffing a hole in the tube after a while of riding. An overkill perhaps, but what the heck!