Recently, I was working with a customer on improving the roll-ability of a few moving dollies she had. There was nothing unique about her application. All she was looking for was a caster that provided a quieter and smoother roll. She found the general duty casters on our website and narrowed her selection down to a hard rubber caster vs. a soft rubber caster. The only question she had then was, what is the difference between the two? They are both rubber, right? The more I thought about this question, the more I realized how often I get asked this. In the sections below, I am going to highlight the differences between these two materials to help you better differentiate between the two.
Starting with the hard rubber caster, as the name suggests, this caster has a harder wheel material. You will be able to tell the difference between the two by testing the wheel tread with your fingernail. If you cannot push your fingernail into the tread of the wheel, it is a hard rubber wheel (If you can push your fingernail in to the wheel tread, it is a soft rubber wheel). The hard rubber wheel has a solid hard rubber tread & core which offers high impact strength. Since the wheel tread is so hard, it will not compress under heavy loads providing for easy rolling and a increased weight capacity. These casters have a nylon bearing sleeve molded into the wheel core which again offers improved roll-ability. The warning against this wheel material is if you have a soft flooring surface, you should be careful because these can dent and scratch floor materials. These would not be recommended for surfaces such as hard wood, linoleum or terrazzo. Usually the wheel color on a hard rubber wheel is a dark grey.
For the soft rubber wheel, again as the name suggests, this wheel has a softer wheel tread. When testing the wheel tread with your fingernail, if you can push your fingernail into the tread of the wheel, it is a soft rubber wheel (If you cannot push your fingernail into the tread of the wheel, it is a hard rubber wheel). The soft rubber tread is molded over a hard rubber core. These wheels have a good shock absorbing cushioned ride, which offers floor protection and a quiet rolling operation. They come with a nylon bearing sleeve molded into the wheel core which offers improved roll-ability. In opposition to the hard rubber wheel, since the wheel tread is softer, it can compress under heavy weight loads. This would make them harder to push and it decreases the load capacity on these casters. Usually the wheel color is solid black.
I hope this helps make it more clear as to when each of these wheel materials is the right fit. Both of them have their pros and cons and are very different from one another.