Certainly you would want to address the wheel issue if it is getting bad. Any CEL's as a result of wheels would likely be triggering traction control messages for the most part or possibly anti-lock brake messages unless it was real bad and causing some weird drive train issue. This may be the case if you are actually experiencing a really bad wheel bearing issue that might be putting stress on the drive train. Has your mileage gone way down or have you noticed acceleration or braking changes aside from the change over to the gas engine?