Material Information


RWM – Pioneers in the field of Urethane Wheels

RWM always strives to offer its customers the absolute best in material quality because we understand that there is no benefit to anyone by using sub-par materials. Having to replace a poor quality part always costs more than purchasing the quality one in the first place.

RWM Casters has always been known as the leader in new product development and has put its extensive experience and engineering capabilities to work towards sourcing, testing and producing wheels using the best possible material.


There are two primary types of polyurethane. They are known as PPG and PTMEG. While the rest of the world uses PPG compounds because they are cheaper, RWM knows that a superior wheel is produced using the PTMEG material.

The following are the properties that are used to compare different polyurethanes:

  • Tensile Strength – A general accounting of the strength of the material
  • 100% Modulus – The force required to stretch the material to twice its original length
  • 300% Modulus – The force required to stretch the material to 300% of its original length
  • Elongation at Break – The amount you can stretch the material before it breaks
  • Die C Tear and Split Tear – These properties are measures of the material’s resistance to tearing. Two different test methods are used to obtain this information.
  • Compression Set – This value measures the material’s resistance to permanent deformation.
  • Bashore Rebound – This how well the material absorbs a shock such as a bump in the ground.

RWM Casters Improved Urethane Properties

Between the PPG material used by other companies and the PTMEG material used by RWM, it is plain to see that the PTMEG material is the superior of the two types thus giving you a superior product for your application. Below is a table comparing two type-representative materials.

Urethane Properties
Tensile Strength (PSI)45107500
100% Modulus (PSI)17052200
300% Modulus (PSI)35605000
Elongation at Break (%)335350
Die C Tear (PLI)385400
Split Tear (PLI)134130
Compression Set (%)2932
Bashore Rebound (%)3748

So What Does This Mean To You?

When you buy from RWM Casters, you can be confident that you are getting a wheel that will last longer, take higher loads, absorb shock better, resist abrasion and tearing, will not flat spot and simply provides a better value to the customer.

RWM’s Urethane Wheel Line

Wheel Hardness Comparison Chart

Wheel TypeTread MaterialDurometerScale
SRSoft Tread Rubber70 – 80A
HRHard Tread Rubber75 – 85D
DUPhenolics145 – 150R
UI, UT, UO, UW, UP, UA, INFPolyurethane90-95A
UI, UT, UW80 A Polyurethane80-85A
UI, UT, UW, SU, MU70D Polyurethane70-75D
RI, RA, SWRubber70-80A
RPGray Rubber70-80A
POPolyolefin, Polypropylene55-75D
SWEHT Rubber65-70A