Just put new shoes on my car - P Zero's. 5k miles on them. Left rear has about 70% tread. Right rear is worn down to around 25%...Front are fine. I thought about camber but wouldn't both be worn? Could the tire be defective? Thanks for any advice.

 

tire could be defective but most likely alignment on right rear..camber or toe (adjustments left and right are independent) you didn't say if the tire was worn on inside, outside or evenly, cupped, crowned...typically P cars wear inside edge on rear if too much camber

 

Remember- there are 4 tires on the ground and the axles are not independent.... The other 3 tires can influence the wear on a fourth.

You probably have too much toe on the rear tires. Not sure on this car, but I prefer keeping it as close to zero as the factory spec allows. Dealerships just check to see if it is 'in the range'.. you want to spec it WITHIN the range.

 

+1 for Alignment.