This is version 1.1 of my road bike tire watch band. More to come as I'll add instructions on how to make the removable cloth piece for extra comfort. Having the road bike tire against your bare skin doesn't feel so good.

Parts:

1 Road bike tire - recommend a used 700x21-25c road bike tire size where the middle is worn down. This wear will make it easier to install the watch.
2 Rivets
1 Sports Watch - keep the pins from the previous band.
+6inches of Velcro - approx 1.5cm width recommended
Thread
(optional) cloth - 10x3inch sheet approximately - cycling jersey recommended

Tools you will need:

Sharpie or felt tip pen
Pair of Scissors
Sharp knife
Pin
Leatherworking punch set
Rivet setter (in most Leatherworking tool kits) OR Rivet press (expensive!)
Sewing kit or sewing machine
Pliers (needle nose)

Step 1: First Cuts and First Outline

Select the section of the road bike tire and place the watch on top of the tire (with the old watch band intact).
Mark the both ends where you will cut, giving your self about 1/2 inch to play with.
Make the first cut and wrap the road tire around your wrist. How does it feel? Look at the 2nd mark and make sure you have about 2 inches of the road tire overlapping. The section that overlaps is where the velcro will go.
Once you've made your final cut, Disconnect the old watch band from your watch and keep the connecting pins.

Step 2: Final Cuts and Outlining

Place the road tire flat on the road with the inner side facing up. This is where you'll make an outline of the watch onto your tire; do so as accurately as possible. Most importantly- the spacing between the two pins.
Draw lines where the pins would be on the outline of the watch. You'll have 2 parallel lines
Now, measure out the middle point between the lines, and draw a third parallel line (equal length) between the pins.
Cut along this middle line with a knife - be careful!!!
Draw two more lines connecting one end of the pin to the other (they should be perpendicular to the line you have cut at step 4.
Cut along these two lines
Test this new cut out. Install the connecting pins onto the watch and loop each end of the newly cut sections around the watch pins. recommend you loop them from the face-end of the watch down to the back, this will be your connecting-pin-loops.
Thread a pin through the rubber to mark the points where the rivets will be. choose the points as far from the edges as possible. You should have markings for 2 pairs of holes for the rivets.

Step 3: Rivets

Using the rivet punch, punch out the holes for the rivets. If you're not sure which size hole to use, choose the smallest possible and work your way up to the hole where the rivet fits snugly. Be careful, the hole puncher ends are sharp!
Loop one end of the connecting-pin-loops, and thread a rivet through the two holes. For comfort-sake, allow the flat end of the rivet to face the inside where your wrist will be.
Place the flat side of the rivet onto an anvil or stable and hard surface. I recommend you choose this spot carefully. The force of installing the rivets can crack bricks, concrete, and dent most metal surfaces.
Secure the tire with something heavy (or a trusting friend's hands).
Center the rivet setter as vertical as possible on top of the rivet. Make sure it is centered
Strike the top of the rivet setter with firm blows from a hammer (not a mallet). It should take no more than 3 blows to set the rivet.
Thread the connecting pins through the connecting-pin-loops.