I heard that it is recommended to replace all four on AWD systems. If just one or two is replaced then there is a risk of damaging the AWD system due to different circumference of the tires.

Has anyone replaced one or two tires instead of all four? Did anything bad happen to the AWD system?

 

Yes I have replaced one tire many times with NO adverse effects (the '07 RL is now passing 165K miles)!! The Discount Tire guys sell this hard, principally because apparently Subaru is adamant that their AWD system can't handle it.

So I checked, more than once, with Acura techs and they assure me that the car can handle the change. "This car has sensors all over the place." I have never heard of a failure caused solely by tire size difference.

 

Did you replace it with the same make and model?

My dilemma is I have one cupped tire but the rest are ok with plenty of tread left, albeit they are 6 years old with date of manufacture March 2015. They are Continental Extreme Contact DWS06 and I'd hate to replace them when just one is bad.

The RL owner's manual states:

It is best to replace all four tires at
the same time. If that is not possible
or necessary, replace the two front
tires or two rear tires as a pair.
Replacing just one tire can seriously
affect your vehicle’s handling.

 

There's your answer.

Replacing both front or both rear tyres is totally fine, but swapping a single tyre is going to give you mismatched circumference between the left and right. This may or may not cause issues, and on the RL the front and rear diffs operate differently, so it may be a bad idea at one end of the car but OK at the other...

 

I think replacing all four makes more financial sense then replacing just two. Might as well take advantage of places that offer buy 3 get 1 free deals.

 

"I think...", "This may or may not...". Jesus, why deal with a bunch of guys basically speculating on this important issue, call the Acura guys and talk to them!! Yes, there IS a spec on this and they can enlighten you on the risk if any.

 

There's no more speculating because I replaced all four. When in doubt, just replace all of them