Hello All,
I wanted to provide some information on the orange wheels...
The jrx2 originally came with the light orange wheels. These wheels were made from a very brittle material. Small cracks developed around the bearing holes because of stress and the type of lube that was in the losi ball bearings. This is the wheel that you can not dip in acetone because it will melt.
About a year and a half later, losi released the following colors:
yellow
wild red
white
new slightly darker orange
These wheels were made from a different material which is similar to nylon.
Below is a picture where you can see the slight differences in color:
Left - Yellow
Middle - Original light orange
Right - New dark orange
UPDATE new information added:
There's also a clear wheel that was made using the newer type of plastic. We all recently saw the gray wheels (thanks Rich)...but I believe those were strictly prototypes...never seen or heard of those before.

- gray wheel 2.jpg (18.79 KiB) Viewed 2529 times

- gray wheel 2.jpg (18.79 KiB) Viewed 2529 times
Hope this information helps...
Regards,
Roger