Most makers are moving away from traction tires. A few provide both. Most modelers remove them, swapping them out by replacing the driver with another. Tires cause two problems; 1. They don't allow the locomotive to slip under load, making the motor overheat and ultimately burn out. 2. While they do help the engine pull more, they are usually out of round, causing an unsightly wobble or they make the engine jump and bounce under load. The best way to increase tractive effort is to add weight, being careful not to overload the motor or reduce the loco's ability to slip its drivers.