If you hit a thorn, nail, or another object that deflates your tire, you'll often only need to replace the inflatable tube inside. Here's how!
The GRIT Freedom Chair uses standard mountain bike wheels, which means replacing a tube doesn't require any special treatment or expensive, wheelchair-specific parts—your local bike shop will have everything you need and will more more than equipped to swap a tube out for you.
The tube you'll need is 26 x 1.5/1.75" and uses a Schrader valve. Note that the Pro model uses tires that are 26 x 2.00"; both these tubes and dedicated 2" tubes will be compatible.
But if you're bike-savvy or feel confident changing the tube yourself, go for it! Here are some links, videos, and step-by-step instructions you may find helpful:
1) REI: https://www.rei.com/learn/expert-advice/flat-tire.html
2) RideOn Magazine: https://rideonmagazine.com.au/back-to-basics-how-to-change-a-bike-tube/
3) WikiHow: https://www.wikihow.com/Replace-a-Bike-Tube