Some people complain that the o-ring tires do not provide enough traction. To address that, I have created a modified wheel, which uses Pololu’s silicone tires. The wheel is a very minor variation of original wheel design; it has the same diameter, so it can be used without making any changes to the rest of chassis.
The design files are available on Printables: Wheel for XRP robot - pololu tires by shurik179 | Download free STL model | Printables.com
PS. This is part of my ongoing project of making a customized XRP robot for my own teaching needs. I am documenting my progress on Hackaday: Customized XRP robot | Hackaday.io
If it is OK with moderators, I will post some updates here - hope it will be useful to other users