nonoise,
Thanks for the information and links. I too learned some of the same today on this, I called Tilite who relayed the tabs represent the width between the tires and handrims. And the default is long tab on the chair. I think I'll go with the Q grip.

spinner,
Good to hear. Why do you find the TR is better for you to transfer in/out of the car versus the ZRA?

EmilyL,
Thanks for clarifying the lateral supports, I contacted Ride who confirmed as well.