Just taken my Cayenne to have two new tyres fitted. Currently 6mm on the fronts, and 2mm on the back. I wondered about putting the new tyres on the front, and moving the front 6mm ones to the back, since the fronts will wear quicker under steering. But the garage said you should always put new tyres on the back, and won't do it. Are they correct, or just trying to avoid a little extra work?

 

Replace all 4 and don't worry about it. tires are your cheapest insurance you'll ever have.

 

I assume all 4 tires match brand and model?

Just rotate in about 5-10K miles and don't worry about it.

 

Always put the better tires on the back. Having better traction in the read helps prevent the rear end from swapping under loss of traction. That said on awd i like to keep all tires about the same and change front to back fairly often.

 

On an AWD vehicle, there's something to be said for putting the new ones with deeper tread on the front to make the front less prone to hydroplaning. It's best to rotate them frequently so you wear out all 4xat the same time since the stability control systems work best when rolling circumferences are all the same.

 

I could be wrong on this, but my understanding was that the rears wore faster than the fronts due to the transfer case proportioning.

 

Yup, rears wear faster. That's why rotation is important to wear out the set together. On some cars that run staggered setups (like all of the Porsche sports cars) that's not possible, but on most Cayennes the setup is square, so it is.