No to solid tires.
I worked construction when I was first out of high school. We would often have to move wheelbarrows fully of wet cement or other such items.
Once while attempting to patch a tire I asked why not solid. The answer is that with a heavy load the inflated tire acts like a shock absorber and has much lower rolling resistance over rough ground with a full load. The guys on the job site told me that solid tires are a mistake that only gets made once. You learn quickly.
In any event the tire is not the point of failure the nylon bearing is.
I would bet if you checked Grainger.Com you find a wheel to fit you needs.
I have never seen ball bearings on a wheelbarrow. I suspect what you will find is a bronze sleeve which will work just fine.
This one looks like the best one for the money, IMHO.
And I think I should know, I’ve pushed many a wheelbarrow full of concrete and dirt in my day. 
(bolding mine)
I’m gonna have to disagree with you on this point. A properly inflated wheelbarrow tire does offer some (read, very little) ‘shock absorbtion’, but not much.
The primary advantage of a pnuematic tire is that on softer ground, (when properly inflated) they will offer decreased rolling resistance.
The trouble with pnuematic tires is that they seem to always be underinflated, which leads to higher rolling resistance.
(And it seems to never fail that when the time comes to get out the wheelbarrow to use it, the damn thing has a flat tire and needs patching. :mad:)
I speak from many years of experience moving dirt and barrows full of wet concrete.
I’ve been a general contractor for 20+ years and all of my wheelbarrow tires (I have 5 wheelbarrows.) get filled with foam the first time that they go flat. 
The loss of ‘shock absorbtion’ does not outweigh the increase in rolling resistance over soft ground, and for that matter, you actually get decreased rolling resistance with a solid tire over hard/solid ground. (Think of a railroad wheel on a steel rail.) YMMV
(bolding mine)
Check out the link in my previous post (#22).
I like my Gorilla Cart. The handle turns around to become a trailer hitch to tow behind the mower. I’ve hauled it full of bricks and broken up chunks of concrete. And it tips up to dump.
Thanks for the advice, everyone.
In doing a little more looking around, I think I’m going to with this Marathon contractor grade wheel. I’m not heading down to the store until tomorrow, though, so there’s time to change my mind.
The wheelon the Kobalt model suggested by JBDivmstr also looks like it might be good, but I didn’t see any mention of ball bearings. I think it just uses a steel sleeve around the axle. I’m not sure if that’s good or bad, but I also can’t find any cite that gives me a weight capacity to compare it to the Marathon wheel suggested previously (500 lbs) or the Marathon wheel I just linked to (600 lbs).
Of course, I have to take the weight with a grain of salt. The wheels I’ve been using appear to be rated at 300 lbs. I suppose there can be that much pressure when in action, but I’m obviously not filling it anywhere near that full.
I haven’t ever had a flat-free wheelbarrow tire, but I think I want to try one. I’ll see what I think of it after using it. From the reviews I’ve read online, it looks like Rick and JBDivmstr represent the two most common opinions - everyone seems skewed one way or the other.
Going back to the issue of ball bearings… some reviews online have talked about needing to oil and otherwise maintain the bearings. I have to admit I’m ignorant on that subject. Any tips on what I need to do to keep everything in good working order?
Here’s a pic of how ball bearings operate and a little info on how to to maintain skateboard bearings. The principles are the same.
The quality of the steel used to make ball bearings and bushings/sleeves makes a difference. Cheap steel is no better than the nylon bushing you had.
For a wheel operating in a dirty environment it’s best to have “sealed” bearings. The wheel should turn smoothly. Lift the wheel off the ground and give it a spin. (You could mark the tire to make it easier to see how many revolutions it makes for future reference but a bearing that goes bad will be obvious. The wheel will turn much slower and/or make grinding noises.)
Ask the store if you’re buying sealed bearings and how to properly maintain/lube them. Hopefully they’ll know. Some bearings are “press-fit” meaning they’re pressed into place under pressure (a C-clamp, jack, or hammer). Some are held in place by a washer and nut. If they’re pressed into place you’ll need to pull or pound them out to maintain/replace them.
Sometimes there are water tight zirk fittings to add grease (but that’s kinda olde skool) and you’ll need a grease gun to force grease into the fitting to grease the bearing. And you’ll need the proper grease.
http://saeproducts.com/zerk.html
There are also dry-lubricant bearings that might not need any maintainence. When they go bad, you replace them.
If the tire/wheel reviews mention bearing failure, I would probably not buy that particular wheel.
Get a red one. So much depends on it.
Everyone knows red ones are faster. 
Damn! Mine is orange, so maybe I’ve been wasting my time thinking about wheels. :smack:
It’s a Yard King! That is a quality barrow.
I don’t think pneumatic tires on a wheelbarrow are a good idea. They end up underinflated, or flat, and they decrease stability. In my lifetime I’ve only seen pneumatic tires used in cheap wheelbarrows, because the wheels cost less than solid ones. My experiences are limited though, that may be just coincidence.
Just be sure not to leave it out in the rain near the white chickens.
Yeah but they get more speeding tickets.
I just wanted to thank everyone for all the advice again. I went ahead and bought the contractor-grade wheel I linked to (which apparently Marathon only makes for Lowe’s).
20 loads of dirt later, and it’s still working. I am keeping the loads a little smaller just to be on the safe side.
The included spacers were too short, but I had the spacers from the previous wheel and trimmed off a little from those to make them a perfect fit for the new wheel. The new wheel is also bigger (at 15.5" instead of 13.5") and so I have to keep on eye on the metal bracket at the front of the wheelbarrow. If it gets tweaked out of position when I dump the dirt out, I have to tweak it back or it rubs against the tire. I think I can do a little modification to remove that annoyance, but it’s a minor issue.