Picking up a new C350, dealer switch rims/tires instead of shipping a car from another location. What is acceptable mileage on 18'' tires taken from another vehicle. Should I ask for new tires?

 

Depends on the specific tires. Sporty, high-grip tires usually don't have long lives. You can look up the tire online and find out what the life is, or the tread depth when new. Most tires are 10/32". You can also check the mileage of the car they're taking them off of.