There are two options for tying the rebar. Either plastic cable ties or wire. I use cable ties. The argument for cable ties is that they will not rust. For horizontal rebar and simple joins in vertical rebar, I find cable ties are quicker to use than wire.
The letter R in a tire size stands for Radial, which means the layers run radially across the tire. Wheel Diameter is the size of the wheel measured from one end to the other. It tells us the size of the wheel that the tire is intended to fit. A size P215/65 R15 tire is made for a wheel with a 15 diameter. Load Index indicates the maximum load that the tire can support when properly inflated.
(Smaller bikes use wheel diameter, too). However, in a bike shop that deals with a few brands, the measurement does refer to the post of the frame (from seat to pedals). Take it for what you will.