Installed on a cart used by young adults that fold and transport a 350# tarp 3 nights a week across many door frames and cords buried under tarps.
Past wheels caved under the pressure.
Theses have held up so far.

At first I tried some 3" casters on my rolling lumber cart in a garage workshop. They always hung up in the expansion joints in the cement slab, and with 500+ lbs of wood in the cart they were difficult to get moving and then hard to control once in motion. Any obstacle such as a stray nail or wood chip on the floor stopped them cold.

Then I upgraded to these (the 6 1/4 inch versions). Two fixed and two swivel casters make the lumber cart easy to roll, easy to control, and able to roll over expansion joints, nails, and wood chips like they aren't even there. It will hop an extension cord if needed and is a lot less likely to damage it than the smaller casters, but I try not to do that. It's nice knowing that I can, though.

I haven't noticed any smell from these, even from the first day. The only down side of these I can think of is that I'll have to make sure to keep the lumber cart inside the garage threshold, well above the sloped driveway. They roll so smoothly that if the cart ever got away from me my neighbor across the street would get 100 or so board feet of assorted hardwood and a new garage door. Which wouldn't really be the fault of the casters.

5 stars so far because they come with an oil fitting and a paint job that isn't flaking off. I appreciate how the edges are chamfered, but I didn't like the initial smell of the rubber. I was concerned about this, but the overall ratings here made me give them a try. Here's what I did. After getting my 8x4s, I left the box sitting outside for a couple of days to see if that helped. No joy. As soon as the sun hit them, I didn't want to be within 10 feet of the box. I hate that smell. Next step clean em up. My product of choice was Ajax Powder Cleanser with Bleach and hot tap water. I soaked a regular sponge in the water, sprinked about 1-2 tsp on the sponge and got to work on the rubber only. I placed the 8x4 on it's side on a square piece of plywood so the tire was free to rotate but the whole assembly was supported. I would rinse the sponge in the bucket of hot water and sprinkle more Ajax on it three times for each wheel. I used a sponge to easily get in the treads without the splatter of a brush. I avoided getting any water or cleaner into the axle bearing or the pivot greased ball bearing area.

I made sure to rinse them before the Ajax and water dried. I splashed a little water into the axle area by accident, but I didn't seem to ruin the bearings the way a skate board will get ruined wheel bearings that aren't sealed the first time you ride thru a puddle.

I left the wheels outside to dry. After four days the smell was essentially gone. How gone is gone? Well like I said I hate that smell and won't stand for it in any way. So I took an 8x4 into my garage and didn't smell it. I walked right up to the wheel and didn't smell it until I got unusually close (hey tire, we're just friends, this is for science). The real test was I put a wheel in my bedroom. I'm sitting next to it and don't smell it.

However, if I pick it up and hold it by the wheel, that smell will get on my hands still. So yeah 5 stars.
FWIW I wanted some with total brakes and am slightly bummed, because while I don't have to invent the wheel,
apparently I have to invent the brakes :)

I used 2 of these fixed, and 2 swivel, casters to upgrade my garage workbench. Previously I was pushing it around on 3" casters which were fine for inside the garage on concrete, but struggled to traverse the weatherlip, and didn't like rolling on asphalt. These wheels are a great upgrade and handle the asphalt fine, as well as the 1" tall lip at the garage door. That said, I wish I had gotten something a little wider. These are about half the width of a normal hand truck tire. If I push the workbench out of the way, into the yard they sink in - even if the ground is dry. The mounting plate is also a little small to be able to get bolts to drive straight in, but that can be managed with a bit extension.

They are pretty good quality and work good for me.