We bought a Dogger years ago to transport our ShihTzu who died recently after providing us with loving companionship for 15 1/2 years.
The stroller accumulated more miles than we could imagine and after all the years of use the tire treads had worn down and become uneven. The two back and single front wheels/tires replacements make the Dogger run as smoothly as when new.
Our new pup rides in the stroller when it is inappropriate for her to be on the ground. The Dogger will probably outlast us even though my wife takes it on a 5-7 total mile daily walk.