Leo Rover v. 1.6 (as well as older Turtle Rover) uses Buehler motors as the wheels actuators. Here you have all the useful resources listed in case you need to access the motors specifications.
Mind the encoder magnets are modified to fit Buehler Motors shaft. Internal hole is redrilled to 3 mm (instead of 1.5 mm).
You can always look for different outer diameter tires, but it will change the rover's speed and force (slope/climbing ability). You can as well find different rubber compounds: softer or tougher ones. Keep in mind that softer compounds will affect Leo Rover's turning resistance, but on the other hand, will help climbing obstacles.
Higher outer diameter = higher speed & lower force
Lower outer diameter = lower speed & higher force
It's always a matter of compromise.
Stock tires of Leo Rover are similar to these: https://www.aliexpress.com/i/32735892787.html
For example, you can look for tires to switch to here: https://www.rcplanet.com/1-10-monster-truck-tires/