Tim has a pretty specialized wheelchair with an out door package, which means he has large knobby rear wheel drive tires. When I was getting our winter tires put on the van I asked if they would be able to change the tires if we supplied them, and they agreed. We haven't done it yet, but do have the tires and tubes with anti-puncture goop in them. We have done so much hiking this summer that we have worn through them in 10 months, and no punctures or flats yet. We have had a couple of brain malfunctions with it, so have a backup PWC from the ALS society of BC, and once used a different one at the VA in Seattle, but he loves his as he is a really big guy.