There are currently 9 different types of tires available. 4 for the Roach, 2 for the Goat and 3 for the Kanga.
You can find them in Radtowns.
They all have different stats, and different model sizes.
Roach Tires:
Sand Hopper Wheel: (Common)
+50 Weight
+30 Traction
+10 Turn Speed
Drifting Sand Hopper: (Common)
+50 Weight
+10 Traction
+10 Turn Speed
Torretto Wheel: (Common)
+40 Weight
+10 Traction
+20 Turn Speed
Billycart Wheel
+10 Weight
+25 Traction
+15 Turn Speed
Goat Tires:
Quadbike Nipple Wheel: (Common)
+25 Weight
+100 Engine Power
+10 Turn Speed
Mangler Wheel: (Common)
+30 Weight
+25 Traction
+15 Turn Speed
Kanga Tires:
Kanga Saw Wheel: (Common)
+25 Traction
+15 Weight
+10 Turn Speed
-10 Fuel Consumption
Kanga Paddlin Wheel: (Common)
+40 Traction
+20 Weight
+10 Turn Speed
+10 Fuel Consumption
Kanga Knobbler Wheel: (Common)
+30 Traction
+20 Weight
+15 Turn Speed