Do It Yourself

It might fill the tire and make it round but it probably won't hold much weight. If it does hold weight it would probably be a rough ride to push that thing around anything that isn't smooth ground. A tire patch like @[email protected] suggested or a plug would probably give better results.

I had the exact same thing happen to me (previous owner left old wheelbarrow). And what I did was take the wheel off, pop the tire out and put a bicycle patch on the hole in the tube. Good as new.

That being said I put probably 25+ bicycle tire patches on in my life, so it was cake for me.

I'd recommend just going for a new wheel and tire. Harbor Freight or your local equivalent probably has one that will fit with a solid tire under $20 and never having to worry about flats or airing it up is worth it.

There's also a solid chance the tire is really old and doesn't have much life left anyway. By the time you patch it a couple times, you've probably wasted more than $20 of your time.